Remus Racing Non-resonated X-Pipe and connection tubes - BMW 3 Series F80 M3 | 4 Series F82 M4ATTENTION: Without homologation! Eliminating front silencer! When installing REMUS down pipes with and without the racing catalytic convertors, which are only suitable for closed road driving, it is important to note that ECU tuning is required to ensure that the engine runs and performs efficiently and to ensure that the CEL does not come on. Tube diameter: Original 65 mm REMUS 70 mm Features Aggressive racing sound Shot blasted surface, 100%