My new 2spd come with a 51T 1st gear and a 47T 2nd...I replaced the stock kit CB 11/15T with a13/17T...this set-up will give me some more top end. If low end torque is what your looking for stay with a low # CB and you should be able to burn you tire`s off the rim...! If your on pavement slick`s are a must. Stock NUB`S won`t last you`ll burn the center`s out. Good luck