youre just paying for names. seriously, theyre billet discs that you bolt up, kinda hard to **** it up, and too simple to say countless hours were spend on RnD.
i have the march udp's. i had them in my closet for a long ass time waiting for a rainy day that i knew would come (you know, the day you want to work on the car but have nothing to install). well i finally did, took a hour or so. pretty much wasted, as there werent even any sotp gains on teh butt dyno. my alternator pully looks nice though.
just sayin, dont expect much. im sure they help in some way, shape or form, and its a cheap bolt on, so might as well do it anyways.