My friend ran a Powerdyne on his 94 GT, ran a 11.27@125 with h/c/i. He ran a 2.93 pulley. They work decent (I ran one as well on a 93 GT) but are limited boost wise. DO NOT waste $$ with 928 motorsports. Run a 2.93 pulley for some more boost but if you want more you will need to upgrade to a Vortech/Paxton/Procharger unit. I gained 10mph and dropped 1 second with a Powerdyne kit on my old GT. I actually liked it due to the stealth factor. I raced a lot of cars and they had no idea it had one.