T-Bird, I think you will be satisfied with the castle 3800, in this truck is feels smooth as silk. Im using a 16t pinion, and I'd say it goes 36-40 mph, with no heat issues. After 2 days at the track my 14t RRP alloy pinion was toast, so I put in the 16t and its much better for the track I run. Oh, ad I ordered som hardened 32p 1/8 bore pinions from Stormer. Will be hitting the track up today or tomrrow to test to see if the 16t is to much.