I've got a 3.23 rear with an M20 so the final drive ratio is 8.13. It's OK for normal driving but it doesn't launch that well. My next large investment will be the Autogear Muncie. Some 3.08 gears to go with that would be ideal for 1st gear final drive ratio and better highway cruising. This table also shows why you need a radical rear end gear to go with the M21 or M22