We have exactly the same problem in the UK. ANY non-Porsche part, no matter what, invalidates the whole warranty. People over here have had warranties refused because the car had an aftermarket battery - yes, this really is true.
Also in the UK, if your car has EVER been worked on by an Indy, you can kiss your warranty goodbye. And yes, lying, thieving Porsche dealers over here are selling warranties to unsuspecting customers just to get the commission - even when they KNOW the warranty is void because the car has been worked on by an Indy in the past.
Have a look here:
http://www.pistonheads.com/GASSING/t...arranty%20Rant
and here:
http://www.pistonheads.com/gassing/topic.asp?h=0&f=48&t=763629&mid=0&nmt=i
This is on top of only getting a 2-yr manufacturer warranty from Porsche!
Compared to the USA it appears Porsche, everywhere else in the world, does its level best to f**k its customers over in the biggest way possible. US customers have it so good by comparison to the rest of us....