After six months of '99 M3 ownership, my impression is that a six-speed manual transmission would be desirable. I would most like to lower the engine RPM at highway speeds, thereby reducing the interior sound level. I am surprised at the engine sound levels transmitted through the firewall in fifth gear and at 75 mph.
In lieu of a six-speed transmission, is there any rear axel gearing readily available to reduce the M3's stock 3.15:1 ratio to say 2.90:1? First gear on my '99 M3 seems "too low" anyway and I often start off in second gear on flat or downhill surfaces. Low RPM torque doesn't seem to be lacking.