Active Autowerke BMW M3/M4 Signature Equal Length Midpipe (G80/G81/G82/G83)The Active Autowerke equal length midpipe for the G80 M3 & G82 M4 provides the advantages of an equal length exhaust system with a smoother high rev sound. BMW provided an equal length solution with the crossover pipe from the short downpipe. However, they overcompensated and made the length of the driver side exhaust longer than the passenger side this equal length midpipe corrects the passenger side exhaust length giving the G80 G82 a true equal