BC Racing ER Series Coilovers for 2008-2013 Cadillac CTS Sedan RWD (GM Sigma II)BC Racing ER Series Coilovers for the 2008 2013 Cadillac CTS Sedan (GM Sigma II) 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 CTS Sedan chassis and refined until it balances ride quality with performance the reason CTS Sedan coilovers from BC Racing are the best selling adjustable kits in their segment worldwide. ER Series