Originally Posted by Soliditude
PE stands for "Performance Exhaust," but not "Edition." The PPK is sold in two stages, 1 and 2. The 1st stage is just the software upgrade - the exhaust is separate.
PE can also stand for "Performance Edition" (same two initials), just as LSD can mean Limited Slip Differential and LySergic acid Diethylamide.
I would never confuse the latter two in a BMW forum, but the former two, I think, is easily understandable.
I am also quite familiar with the PPK stages. I went through a lot to get the stage 2 installed in my non-sport 335i.