BC Racing ER Series Coilovers for 2001-2006 BMW M3 RWD (E46)BC Racing ER Series Coilovers for the 2001 2006 BMW M3 (E46) put race grade adjustability in reach of the serious track day driver, with independent compression and rebound tuning at every corner. Every kit is extensively tested on the M3 E46 chassis and refined until it balances ride quality with performance the reason M3 coilovers from BC Racing are the best selling adjustable kits in their segment worldwide. ER Series kits run a linear twin piston