I completed the spark plug replacement on my 718 Boxster (base) this weekend.
I used a lift and removed both rear wheels to access the ignition coils & plugs (2 on each side of car/engine).
On the driver side, you can access and remove the ignition coils & plugs by only removing the wheel and nothing else.
On the passenger side, there’s a small heat shield that must be detached by loosening 3 bolts before you can access the 2 ignition coils & plugs.
My opinion is that you must have a magnetic swivel spark plug socket
(14mm, 12 point) for the removal and installation of the plugs. I don’t think I could have completed this task without the magnetic & swivel features. Here’s a link to the one I used:
Amazon.com: ARES 11000 - 14mm Thin Wall Magnetic Swivel Spark Plug Socket - 3/8-Inch Drive 12-Point Spark Plug Socket - Walls 2mm Thinner Than Standard Spark Plug Sockets: Automotive
I forgot to write down all the socket sizes for the removal of the screws/bolts on the ignition coils & heat shield, but they were all common Torx, E-Torx, and/or metric sizes.
Your working space is fairly restricted inside the rear wheel area, so it also helps to have wrenches/drivers with different handle lengths and a few different socket extension lengths. A flexible extension is also helpful for installing the new front spark plug on the passenger side.
FYI, the most difficult plug to access is the front plug on the passenger side. I ended up using a wrench with a swivel extension along with the magnetic swivel spark plug socket (yes, 2 total swivels) to remove and tighten down this plug.
I read that the torque is typically around 22ft-lbs for the installation of new Porsche spark plugs, but I was unable to get my torque wrench inside the work space very easily.
Once I started tightening down the plugs, I felt that 22ft-lbs might be too much and didn’t want to risk over tightening the plugs. I tightened down all the plugs as much as I could with the socket wrench and would estimate around 15ft-lbs if I had to guess.
As usual, make sure to use some anti-sieze on the threads of the plug and dielectric grease on the inside of the ignition coil where it connects to the spark plug.
I hope the above information will help some of you 718 forum members.
If you have access to a lift, I think this is a reasonable DIY service task.