Tough choice. I like the turbo 400 with the gear vendors over drive. What is sweet about that setup is you actually end up with a 6 speed transmission instead of a 4 speed. What purpose the 6 speed would serve is beyond me but I have been known to go to excess just because I could. You could even load the turbo up more by have the o/d unit engaged at the starting line. That's a scary thought, overdriven 2nd gear finishes with 3.07s and tall slicks.