The official Porsche position as I understand it is that any mods made to the intake and exhaust are of concern and likely a warranty killer.
Certainly, the local dealer does not like to work on cars that have aftermarket items of this nature. Having said that, they do have diagnostics that could tell you if your car is running lean or rich and by how much. This is much more sophisiticated than relaying on your CEL to tell you.
As I understand it, yours car's computer can make adjustments to the f/a ratio WITHIN CERTAIN PARAMETERS. If the ratio is way out of whack, my guess is that you would get a CEL but I am not certain.
I will ask the service guys later today.
You are correct in being concerned about any f/a alterations as nothing good can come of them. Fouled plugs to lunched pistons, it is all bad news.
