In Reply to: M3 Six-Speed Manual Trans & Rear Axel Ratio posted by dn on January 09, 2000 at 13:11:16:
A 6 speed tranny would be exspensive, and most likely void your warranty. A rear diff wouldn't be as exspensive, but might also void your warranty. A better and cheaper idea would be to buy some sound-deadner such as Dynamat. Remove the carpeting and applie it to the floorboards.