All I did was remove the center resonator and replaced with a $70 X pipe. Got all the sound I needed and it sounds GOOD. Best sounding bang for the buck on any Bimmer I've done.

I should include that I've used SuperSprint on my BMW's including my 1975 2002 and my 2000 supercharged 540 with SuperSprint headers. I am pretty picky about the sound in my cars. I even removed the dual exhaust after installing it because I thought the sound was too much like a Chevy truck to my ear. The SuperSprint was just right.

540 headers:

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