What exactly are you looking to do? why are you looking to change?

On the track I spend most of my time, I've settled on either 19 on pinion or 20 BUT I am running an 83 spur. With some modification, I would like to try a 16 with that 83 and shoot corner to corner but that's for later testing.

Simply moving up on the pinion from stock will get you more top end but even in stock trim, most tracks don't have the space (around here) to top out the truck. I find I am better being slower on the top end, just get there faster, why I've settled with what I am running 20/83