they change your cars stock tuning through the ecu and yes they really work...ive got the speeding ticket to prove they work hahaha
93 325is - SOLD (white car in sig)
92 325i - 220rwhp/205rwtq (RIP)
02 GSXR 600 - 107rwhp/48rwtq
95 M3 - 220rwhp/205rwtq
President & Founder OF S50 Swap Club
THC the three most powerful letters in my veins...