The M2 CS is the most highly tuned version of the S55B30, at 450hp, and therefore the most demanding on its bottom end. This page brings together the ZRP and MANLEY forged connecting rods listed for…The M2 CS is the most highly tuned version of the S55B30, at 450hp, and therefore the most demanding on its bottom end. This page brings together the ZRP and MANLEY forged connecting rods listed for the N55B30 and the S55B30 alike, the JE, MANLEY, WÖSSNER and DIAMOND forged pistons in 84 to 85mm with a 22mm gudgeon pin, and the ACL RACE and KING RACING tri-metal bearings for big ends and main journals. The valve train is uprated with SUPERTECH and FERREA valves, CATCAMS springs, stem seals and collets. The head gasket here is the COMETIC S55B30 part shared with the M3 F80 and M4 F82.