Watch any type of solid bushing control arm, be it either the uppers or lowers, if you drive the car on the street a lot. You will need to keep them greased and after time, the bushings will eventually wear out. You might want to look into something with some poly bushings like the Mega Bite Jr's. My short times were 1.51 with these. If you are looking for a lot of traction, get some 90/10's and chuck the whole 70/30 idea to the weeds. In my opinion they aren't worth wasting money on. Like Derek said, keep an eye on your pinion angle. It can hurt just as much as help. It all depends on where you have it set.