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Discussion Starter #1
Hello Everyone,

Say hello to our new R&D project, the 718 GT4! There’s been a lot of talk over the last few months about this car and a lot of discontent with some popular YouTube videos comparing the 718 GT4 and 981 GT4. Let’s dive right into it. More photos and videos will be forthcoming as we progress with development. The new 718 GT4 (and Spyder) as shown here now has three modular exhaust sections compared to the previous 981 generation that had two. Starting at the front, we have the headers and primary cat assemblies. The exhaust then bolts to a set of over axle pipes with canisters at the end, which then connects to the factory valved muffler system



The Headers (Primary Cat Assemblies)

Some of the immediate low hanging fruit that pops out is a rather restrictive merge collector that essentially has all three primary tubes hitting a wall, at which point the exhaust flows into a cat core just as dense as they have been before on previous Boxster / Cayman generations. We’ll get a bit more in depth into this once we take a closer look at the headers this week and come up with some prototypes. We will be making a catless long tube competition header and street header utilizing HJS HD 200 cell cat cores. With the superb new rear aero improvements, clearance is TIGHT from the headers to the underbody panel, so we may have to get creative with this header/merge collector design.


The Over Axle Pipes

These factory over axle pipes appear to have a faux OPF matrix completely unmonitored by the computer system, unlike the Euro spec cars with monitored OPF cores. These were the first to go, and as you can see and hear this is going to be one of the best returns on investment for sound and performance improvement with a single product replacement. Uncorking these over axle pipes makes much better use of the factory valved PSE muffler. It maintains a very reasonable, almost factory-like sound inside of the car with valves closed, and valves open it is quite transformed. Eliminating the restriction of the headers and over axle pipes and keeping the factory PSE on the 718 GT4 / Spyder will without a doubt be the golden ticket setup for this platform.




The Rear Muffler Section

Yes, California and European owners we’re listening! For you Cali folks, until we confirm these over axle pipes don’t have a true emissions control device in them we realize this is the only piece of the exhaust you can “technically” replace while passing inspection / emissions as there are CARB visual certifications requiring factory only components, even though you have a 6 year grace period if I recall before you have to go in for that. For our European friends in particular, we know you can’t touch the over axle pipes due to the monitored particulate filters as there is no high flow aftermarket replacement for those units yet (people are working on it) so that leaves the headers and the rear system. This factory PSE muffler is pretty well designed, albeit pretty funky looking to clear the rear diffuser. With valves closed it significantly cuts down on sound through the muffler body and with valves open it essentially bypasses the entire muffler assembly (diagrams / photos / video on this soon). However, if you’re looking to stay emissions compliant in your area it’s the only piece that can go and so it shall. We intend on offering several different versions of muffler replacement on this car - something wild for those that just don’t care and want to drop as much weight as they can, and something valved to have a similar wild factor but the ability to tone it down and take the edge off the sound to fly under the radar. The space constraints with the diffuser will make this complicated, but we’re up for the challenge and will start playing with the rear exhaust configurations once we complete header and over axle pipe development.



The Exhaust Tips

Unlike all the previous Boxster/Cayman generation that had welded on tip assemblies, the 718 GT4/Spyder has bolt on tips...finally! This is going to be an easy project, and expect a flurry of different tip options from us soon to kick up the cosmetic appeal on the backside of the car.

PSE Programming

This is where things get interesting. European sound restrictions have been getting more and more severe over the last decade or so. Every time a new GT car comes out from Porsche, the PSE programming becomes more and more invasive in controlling the sound level of the car on full throttle. As many of you I’m sure have experienced on your previous Porsches, even with the PSE button pushed the programming will override this and close the valves until you reach a higher rpm range. The 718 GT4 is no different, and in fact it’s worse. With the button pushed, the 991 GT3 I drove the other week would shut the valves on hard throttle and then reopen around 3500rpm. With the button pushed, this GT4 keeps the valves closed until about 5000rpm. Now more than ever, the most inexpensive mod on sound you can perform on a GT car is unhooking the vacuum lines from the valves and plugging the lines so you don’t have a vacuum leak. Especially when unrestricting the exhaust upstream it makes a huge difference. Take the over axle pipes for example, below is a video where I drove this GT4 with our prototype over axle cat delete pipes. There are two takeoff clips in that video, the first take off clip is with the vacuum lines pulled and the valves in the default open position. The second take off clip has a large truck in it, during this one the PSE button was pushed/active for that takeoff and you can hear the valves close and then open at about 5k rpm. Completely different sound experience.

Now, for those who still want valve control but don’t want the PSE programming to override your fun we have one option now and are working on a couple others. We have our universal valve controller kit that simply works off constant 12V power, vacuum, and ground and has been used with great success on all of our valved exhaust systems for Porsches over the years. On this car it would serve to override the PSE button so it will no longer function, and the key fobs with our kit control the valves 100% closed or open. You can also sync the signal of these key fobs to your garage door buttons of the HomeLink system, so you can use existing buttons in the car instead of the key fobs if you so choose.

A second option may be an ECU tune. I’ve spoken with Scott at Softronic, our dedicated Porsche tuner. Many of you know him as one of the most experienced in the industry specializing in Porsche tuning for over 30 years. PCA Club Racing uses Scott to check all the ECUs to make sure no one is cheating, he also tuned all the Cayman Interseries cars, winning GTB1 cars, etc etc. He intends to look into the PSE programming itself to see if he can reprogram the ECU to simply keep the valves open 100% of the time when you press the PSE button. Along with all of the other benefits of software tuning Scott offers - such as power - this would be adding icing to the cake. We’ll look into this option for GT3’s as well.

A third option is our friends over at DSC, those suspension tuning wizards you’ve all come to know and love for the DSC suspension modules to maximize the potential of Porsche’s PASM system. They have been working on an addition to the DSC module that allows you to have full control over programming your valves to do whatever you want when you want. We are keeping in touch with them closely moving forwards (as we are a DSC dealer!) and very much look forward to seeing how this turns out to play with improving the valve control and suspension on this new platform.


-Mike Spock
Marketing Manager
 

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Sounds amazing!
Do You know if the 2019 base 718 Boxster also has stringent PSE programming?
Mine should also be with OPF, and there is not much sound until it gets up in the higher revs, maybe unhooking the actuator would gain me a bit of sound...
After taking delivery of my 992 Carrera coupe I am a bit disappointed with the sound level in the 718 when comparing it to the 911 as it seems much louder.
 
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Discussion Starter #3
As you aren't stateside, I can't comment with certainty on the performance as the European OPF system is more stringently monitored. We will likely attempt to hardwire in a valve controller as an option for retaining the factory rear exhaust.

Manufacturers are utilizing valves in the exhaust to serve more purposes than just sound control at this point. The C8 for example has secondary valves in the exhaust which close during 4 cylinder mode. The next decade will be very interesting with ECU controlled valve operation and monitored particulate filters - much to our chagrin as enthusiasts and modders.

-Mike
 

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Joined
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As you aren't stateside, I can't comment with certainty on the performance as the European OPF system is more stringently monitored. We will likely attempt to hardwire in a valve controller as an option for retaining the factory rear exhaust.

Manufacturers are utilizing valves in the exhaust to serve more purposes than just sound control at this point. The C8 for example has secondary valves in the exhaust which close during 4 cylinder mode. The next decade will be very interesting with ECU controlled valve operation and monitored particulate filters - much to our chagrin as enthusiasts and modders.

-Mike
Where things are headed we might just embrace the electric sports car... Or keep the cars we have now roadworthy till the end of time :ROFLMAO:
 
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Discussion Starter #6
@Soul Performance Products
Mike, how does the GTS 4.0 fit into this product development?
At this time, it does not. Until we get our hands on the GTS stateside we can't make any assumptions - the US GTS may have different kit than the non-US versions. There are differences between the GT4 Clubsport exhaust setup and the GT4, we can't make assumptions that the GTS will be the same until see factory part numbers. We're working on getting more info.

-Mike
 
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Discussion Starter #7
Here is an update for you guys on what we’ve been up to since starting this thread as we concentrate on the header and over axle pipe development to start.

Competition Over Axle Pipes
Below are a couple photos of our prototype set used in the video we posted. The thick gauge aluminum fixture has been finalized to prepare for production. The bend profiles are currently being 3D scanned to have the primary flow path piping bent into the profile, eliminating five welds on the driver side and four welds on the passenger side. At that point we will test fit the final production version, take professional photographs of the finished product, compare the weights between ours and factory, and release this as the first product available for the 718 GT4 platform in June.

Below is a photo of Porsche’s part numbers for these over axle pipes. Note there are three versions of these over axle pipes - not two - and all three use particulate filters. We know North American versions are all the same and unmonitored, while Europe has the monitored versions. We’re waiting on clarification on what the mystery third set is for the region and if there is any change in the design. The North American version from Porsche retails for $3288 per side, by the way. Huge shoutout to our friends at Suncoastparts.com for working with us on doing a deep dive on this!








Competition Headers

It is very tight on space with the underbody panel on this car and these constraints have made header development a challenge. We’re focusing our initial efforts on a set of competition headers as we don’t have to worry about incorporating a cat core. Below are photos of the prototype headers we have built and test fit. It is especially tight to the engine and underbody panel on the driver-side (left) and requires some additional revision to clear which we are working on as we speak. The first version of these headers - for those that are antsy to get a set - will have laser cut header flanges to the spec of our prototype. However, we are taking these header flanges a step further and have designed and 3D printed the flanges for these headers to be sent out and cast or CNC machined to eliminate three welds per side. These will take several months to receive back and will from that point be incorporated into the headers. Regardless of which set you receive, the laser cut vs cast flanges will have a negligible effect on performance and they will both come with our Lifetime Warranty for both street and track use. Realistically, the Competition Headers could be available in June.














-Mike
 
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Discussion Starter #9
Valved Rear Exhaust System Update

In regards to this topic in particular...The PSE muffler is Very well designed, check out the explanation video below of how. If you want an exceptional valved exhaust system while at the same time uncorking the main performance restrictions on the car, you should strongly consider simply freeing up the flow upstream of the PSE muffler with our competition over axles pipes and perhaps a combination of our headers. If headers and over axles pipes are not something you can do due to stringent emissions restrictions, we are working on a valved rear exhaust solution.

Don't want to watch the whole video? Skip to 3:00-4:30 for our muffler design

We have gone through four versions of different valved rear exhausts on this car and about twenty different iterations of them. This car needs a muffler to kill the drone with valves closed, the drone range is too wide (about 1000rpm) to eliminate completely with traditional resonators and/or a combination of Helmholtz Resonators. That brings it's own challenge, the rear diffuser takes up a remarkable amount of space back there to put a muffler. Unfortunately none of the existing dual entry/dual exit mufflers available on the market were suitably designed in shape, size, internals and quality to meet the goals we have for sound/drone requirements, flow characteristics, spacial restrictions and longevity on this car. Therefore, we designed our own bespoke muffler for the GT4/Spyder/GTS!

The first step was to 3D print a muffler shell to accommodate the spacial requirements on the car. Once this was done, we utilized a chambered x-pipe internal design based off of an extraordinary successful venture designing a one off valved exhaust system for Larry of AMMO NYC's Audi R8. The video of that project is below and its a great watch if you want to check out the whole thing. However, you'll see the muffler design in detail from 3:00-4:30. I've also included some photos below of our rendition of this muffler specifically for the GT4/Spyder/GTS. Due to the complexity of this design and how labor intensive they are, we are having our mufflers made to our exact specifications in a large number by one of the fabrication facilities we partner with. This way we will have them readily available on the shelf to reduce the lead time of getting them in your hands dramatically. We will keep you up to date as this progresses
:cheers:









-Mike
 
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Discussion Starter #10
Race Exhaust Update

As you may have seen in the PSE muffler explanation video in our last post, the factory PSE system is very well designed from a mild to wild standpoint. We still firmly believe that uncorking the exhaust system upstream from that PSE muffler is going to provide an ample improvement in terms of sound and performance to meet the goals of the vast majority of 718 GT4/Spyder/GTS owners. The race headers, street headers, and competition over axles pipes (GPF deletes) are in the final stages of R&D and will be released soon - are you on our waiting list?

That said, some of you may ask... what about the track rats? What about those of us that live in the high rpms and want to hear this car working and maximize the driver’s connection? Those that are in the minority, that don’t value cruising speed comfort as much as weight loss and maximizing flow/sound characteristics. We thought about you too, and this is what we’ve come up with for our Race Exhaust, which can bolt right up to the factory headers or our race/street headers.

The factory dual exit/entry flanges connecting the over axle pipes to the PSE muffler limit the piping diameter to 2.25” - we’ve eliminated those. Our system is full 2.5” all the way as we’ve eliminated the factory over axle pipe to PSE muffler connection. We’re using an X-Pipe to accommodate resonated and non-resonated options. The longer piping routing also helps noticeably smoothen out the exhaust sound while the slight blending of the X gives the car a higher pitched sound more akin to the previous 981 generation we’ve come to know and love. The resonated version sheds 29lbs while the non-resonated variant drops 32.3lbs. The bend profiles are being 3D scanned and our mandrel-bent versions will eliminate a dozen welds from the design. Like all of our products, it is fabricated from T304L stainless steel and back purged with argon gas for maximum longevity under sustained high rpm abuse, and is backed with our Lifetime Warranty for street and track use.






Weights
Factory: 57.4lbs
SOUL Resonated: 30.85lbs (-26.55lbs)
SOUL Non-Resonated: 27.5lbs (-29.9lbs)

Tip Options
This system can be used with your factory exhaust tips, and our upcoming tip solutions will be a direct bolt-on once available (4" Slash Cut or Straight Cut, Double Wall or Single Wall, Signature Satin (Silver), Brushed, Polished, Black Chrome, or Satin Black)













-Mike
 
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Discussion Starter #14 (Edited)
VALVED EXHAUST SYSTEM RELEASE!

After months of development and hard work we are proud to release our Valved Exhaust System. The PSE muffler leaves a lot to be desired, especially with the valves closed as it offers little to no sound level and tone. Valves open it is relatively unrestricted all things considered but keeps the primary flow of the exhaust banks separate, resulting in what we consider to be a deeper and less refined sound than the 981. Even when uncorked and amplified with aftermarket over axle pipes and a valve controller the tone characteristics of the factory rear exhaust remain bland and lack a characteristic desirable higher pitched/smooth tone. I won’t go into too much depth here, you guys know what you don’t like and what you want to improve on as much as we do.

Development Goals
  • Improve upon the factory design and achieve a throatier / smoother / higher pitched tone.
  • Increase the presence and character of the exhaust note in the cabin while maintaining a reasonable level of resonance / drone while driving in both the valves closed and open modes through our signature drone fighting capabilities.
  • Heighten aggressiveness with valves open while maintaining an overall sound level potential / quality that can still be reasonably driven on the street in combination with other complimentary aftermarket exhaust components – such as competition over axle pipes and header replacements.
  • Offer the ability to notably reduce the sound level of the car outside to fly under the radar when necessary.
  • Achieve an effective delta in sound between both modes for two usable, well engineered experiences – mild and wild.
Research and Development/Achieving the Mark

When we first started working on this platform, we tried a variety of non-valved and valved PSE muffler replacements. Straight pipes with and without an exhaust blend (X-Pipe), different tubing diameters, resonators, Helmholtz resonators (anti-drone tubes) in numerous lengths, volumes and locations, velocity cones, and combinations of many of these. In total we tested about 20 different designs / revisions of PSE muffler replacements. While some of these configurations hit the sound / tone we were looking for, none of them maintained what we considered to be a reasonable cabin presence in-cabin at cruising speeds in high gear in low rpms. At the end of the day, this car has an approximate drone range of 1,200rpm (1,800-3,000rpm) with a peak drone point of about 2,000-2,600 which the PSE muffler targets very well with valves closed. Though we could shift or reduce this peak in various ways, we determined that utilizing a muffler was the only way to reduce the drone level across the full drone range enough to meet our goals.

With valves open, our Valved Exhaust System follows a similar design to our Race Exhaust System through an X-Pipe that merges the exhaust flow for a higher pitched, smooth sound. With valves closed, the exhaust is routed through smaller piping and a bespoke SOUL muffler we designed to fit with the X-Pipe in the confined space above the rear diffuser and meet our sound goals. This muffler was crafted to match our high standard of drone fighting mufflers like the rest of our existing Boxster / Cayman line that we have become known for.

Internally this muffler is quite unique. It has little to no restriction in the flow path, using straight through piping that is perforated to allow exhaust gasses to escape and become muffled in the surrounding packing material of the muffler body. We incorporated a second internal X-pipe to allow the exhaust flow to merge smoothly. These characteristics combined were crucial towards reducing and smoothing out the drone in the 1,800-3,000rpm range while enhancing that higher pitched note we were after in both the valves closed and open conditions.

In addition to the bespoke muffler design, there are several other unique characteristics we’ve brought into play on this system which revolve around the secondary flow path entering the muffler. The key thing to note here is that the valves open flow path is not limited to the 2.5″ external X-pipe flow path only, some of the exhaust flow is still going through the secondary flow path even though the valves are open. This design is essentially utilizing the entire secondary flow path and muffler design to smooth out the tone and drone while running valves open. Please note the carefully tuned length of the piping entering the muffler, as the sound waves and exhaust pulses have a longer distance traveled through the piping for a notable effect on sound attenuation. Utilizing this secondary flow path for honing in on the optimal cruising cabin presence, we were able to go aggressive on the design of primary flow path with larger diameter 2.5″ piping without incorporating resonators or mufflers.



Valves Open vs Valved Closed Flow Paths



PSE vs SOUL














3D Printed Muffler Shell For Test Fitting



Internal Muffler Design

Driving Impressions

Changing just the PSE muffler with stock over axle pipes offers a superb change in tone. It is smoother and higher pitched, more in line with the flat 6 character we’ve come to appreciate with previous generations of Boxster / Cayman. The PSE running valves closed had no real tone to it, we’d describe it as tinny, hollow, and rather boring as you can hear more of the intake than the exhaust. With our Valved Exhaust System the exhaust now has real character, and you can hear more of it everywhere with valves open and closed. Expect a smooth transition between valves closed and open modes. With the rest of the exhaust stock, the overall sound level at WOT with valves open may not sound dramatically increased. This is due to how aggressive the flow path is with valves open on the new 718’s PSE muffler. However, on our system the larger tubing diameter, distance traveled, and blending of the X-pipe gives the sound more depth and changes the tone to a smooth / higher pitch song. It sounds incredible especially from the outside, offering a true sporty note one would expect from the high end 4.0L.

We found that the particulate filters in the over axle pipes put a big damper on the overall sound level and how it carries into the cabin. Think of it like a cork in the middle of the exhaust, letting a PSE muffler replacement tease you but not giving you the full experience. Combining our Valved Exhaust System with our Competition Over Axle Pipes is when the skies open up, the sun shines down and the Porsche Gods have blessed us with the sound we’ve all been waiting for. Inside and outside the car, windows up and down, the experience is nothing short of transformational. At wide open throttle it sounds like a weapons grade symphony. Very reminiscent of a GT3 at 9k, and arguably better than any stock GT3 you’ll ever hear on the street. Ditching the factory over axle pipes finally allows the car to have some burble on deceleration but nothing too over the top, just enough and just right. When you do a hard shift, a visceral crack erupts to really put a smile on your face. Not like a shotgun blast going off, more like a reward for actually driving the car how it’s meant to be driven. The sound is aggressive, but not overly so like you just took an RSR off the track for street shenanigans. When you’re off throttle cruising around, it’s relatively docile and comfortable (that secondary flow path at work). If you want to fly under the radar and significantly cut down on sound level outside the car, you simply close the valves and away you go in stealth mode. However, even with valves closed the tone and character of the exhaust is still there, not dead muted like the PSE muffler. It has cabin presence, some ever so mild drone/resonance in low rpms that we consider quite reasonable compared to the other configurations we’ve tested – even with valves open it’s quite reasonable. We’d almost say it’s more a character of the system and it’d be a shame if there wasn’t any to tease you into squeezing on the gas to hear more of it. We highly recommend installing a SOUL Valve Controller Kit to override the PSE programming at your convenience, and hear what it has to offer under 4-5k rpm in the first few gears – it’s worth it!

Valved Exhaust System with Factory Over Axle Pipes with Factory Headers


Valved Exhaust System with Competition Over Axle Pipes and Factory Headers (SOUL Street Package)


North American vs European Fitment

Here is where things get quite interesting. The mounting of the factory rear exhaust system is DIFFERENT between North American and European cars. Therefore, if you are looking at an aftermarket exhaust system that replaces the PSE muffler, it is CRUCIAL to know which vehicle mounting system the exhaust was designed for. Please review the photos below. European vehicles have a support system that connects to the over axle pipes and has two large band straps that go around the factory PSE muffler. North American vehicles have no connection to the over axle pipes, and use two primary posts and a secondary horizontal stabilizer. To install an exhaust system developed on the European mounting system on a North American car, you have to convert to the European mounting system. To install an exhaust system developed on the North American mounting system on a European car, you have to convert to the North American mounting system. We also hear the upcoming PDK models may have a different mounting system for the muffler as well.... That all said, for those fellows in Europe that would like to run our exhaust system, we have the part numbers for all the North American mounting components you would need and we can ship them with the exhaust. Total cost for the mounting conversion would cost about $550 USD.



European Mounting



North American Mounting

Pricing

Valved Exhaust System Product Page: This system starts at $3,795 for use with OEM Tips and Factory PSE control.

With Polished Tips: +$3,995
With Signature Satin Tips: +$3,995
With Brushed: +$3,995
With Satin Black: +$4,095
With Black Chrome: +$4,095

Select Tips Are Available In Slash Cut or Straight Cut, and Dual Wall or Single Wall. We will have all options photographed on the car in due course. Please reference our product page for all pricing and tip options.



Sport Package Product Page: This package consists of what we consider to be the Golden Ticket setup for street use…our Competition Over Axle Pipes and Valved Exhaust System, with optional Valve Controller Kit. Depending on tip options, this package ranges from $,5445 - $,5845. Please reference our product page for all pricing and tip options.



-Mike
 
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