I go with: If it isn't broken don't fix it, but if it isn't there add it.
Porsche knows a lot more than me about building cars, and they made every part of the car specifically to work together, so I stay away from performance mods. Plus, I am perfectly happy with the performance of my car, and keeping some money in my wallet.
My favorite mod so far was the OBC switch, it adds a lot of functionality for only $50, although figuring out the intermittent wipers from the scattered info on the internet was a lot of fun.
