I recognize I could just remove it when I go in for tune-ups but I'd like to know if a PCV would technically voice my warranty?
It's up to BMW. If you sought a warranty claim in the USA and BMW could reasonably conclude damage was caused by, or even contributed by, your Power Commander, BMW would likely refuse your warranty claim. Of course, you could pursue legal remedies to force them to honor the warranty, and some arbitrator or judge would decide whether you screwed up, or not. Hardly worth it, right? Nonetheless, my '09's stalling in first gear while negotiating hairpin forest roads was unbearable, so I installed a similar device (Boosterplug) that solved the problem. "You makes your choices and takes your risks." Fred
Look into the Magnuson-Moss Act. Short answer is that they have to prove that the modification had a direct impact to the issue in question. Here's a some light reading. http://www.impalasuperstore.com/naisso/magmoss.htm
Without being a total ass, this falls under the paranoid category IMHO.. My opinion will get you exactly 1 cup of muddy water when you least want it, so please take it with a grain of salt You stand a better chance of voiding the warranty by not doing routine chain maintenance or farting on Hitlers revenge.:eek1
The Magnuson-Moss Act speaks for itself. Now who holds the hammer? Dealership refuses to warranty a blown up engine? What do you do?. File a complaint that BMW contest. How much money do you have to fight it? Sure its a worst case scenario. Dealers might even handle it differently depending what your relations are with them. Something uncommon, does not happen or a big ticket repair, will get one of the area reps involved. I dutifully took off my temp spoofer, worried about that. Come to find, the Moss unit they hooked up didn't know it was there.