However, the largest restrictive bottleneck for general performance and audio is your turbocharged auto’s downpipes, especially if they have OEM catalytic converters. To be able to Obtain your turbocharged S58 driven G80 M3 or G82/eighty three M4 to sound its greatest, you must swap your OEM downpipes with aftermarket ones. https://bmwm3g80catteddownpipes08642.wikigop.com/557508/considerations_to_know_about_bmw_m4_g82_downpipe