Guys ... I've posted about this stuff in several other places:
- The Bose and Burmester systems are routed through a fiber-optic control unit called a MOST box. The latest MOST protocol for mobile applications is MOST 150, which PCM4 uses for these systems. Aftermarket makers of OEM-integration gear such as MObridge are only just now releasing gear that can deal with MOST 150. Bottom line: It is nearly impossible to upgrade the Bose and Burmester system in the aftermarket.
- The base Sound Package Plus does NOT use a MOST box -- and in the 718, it doesn't even run off of an outboard amplifier like the 981 did. Everything is inside the HU. This is good -- it makes the audio upgradeable in almost every way.
Soooo ... if you plan to (or think you would like to) do anything to improve the audio, do NOT order either the Bose or the Burmester upgrades.
Other notes:
- I am vehemently anti-Bose for a number of reasons I won't get into here. I don't want that logo in my car, and I know others feel the same way.
- I plan on upgrading my car's SPP (yes, I ordered it on purpose) in the spring. The plan: upgraded speakers, a six-channel amp, and a DSP unit. I already have an amp; I can do the rest (and have it put in by an installer with years of experience on Porsches) for less than $2,500 -- and it will sound better than the Burmester.
- The 718 Cayman has rear-fill speakers; the 718 Boxster does not. Why do I mention this? Your priorities in upgrading the audio in each car will be vastly different. With the Cayman's rear fill and 7" door drivers, a subwoofer is almost certainly not necessary if the right replacement door driver and installation is chosen. With the Boxster, a sub will probably do wonders because the car's interior is essentially an infinite baffle when the top is down, and is far less sonically reflective than the Cayman when the top is up. You will want more power in a Boxster, too, because ambient noise will be higher and you'll need it to hear any sort of bass frequency cleanly. Essentially, the Cayman is a SQ (sound quality) platform, and the Boxster is a SPL (sound pressure level -- i.e., volume) platform.