he is looking to run 13.5 4wd at the cactus classic. So I am fairly certain his plan is not to go slow. It is also a non boosted class. So he will need to run 13.5 with motor timing only. Gino. I would start where I said, then adjust for temps. I am sure you have all of the pinions and spurs to try stuff out. 13.5 4wd is just not super popular. But i plan to run 13.5 in my wheeler this weekend and I plan to start where I told you.