Not sure what car you're running, but most brands offer "lightened drive line parts" designed specifically for stock racing, ceramic bearings are a must, I like to run ceramics from
AVID in the Aura single metal shield series. Other tricks to reduce rotating mass are running 2WD wheels up front without foam inserts, not to be confused with cut carpet wheels, I'll still run a 4WD front tire, typically ProLine Prisms, but with no foams up front. Plan to spend between $200-$300 in upgrades to gain a competitive edge in stock racing.