The BMW Motorsport Cam Gear retards the exhaust camshaft of the 88-91 M3 and 88-89 M5 and M6. This allows for better exhaust scavenging, which in turn gives a moderate torque increase. This is very useful in day-to-day driving. This cam gear came stock on the EVO2 M3. (+11 lb./ft torque increase at 3000 rpm on M3 and +22 lb./ft on a M5/M6).