I`ve got 10 years on my 727 that`s in the dart now and it was origionally a Pro-Trans deal then was freshioned up 5 years ago by Darrell Parks and rollerized at that time. No problems at all even w/4.11`s and an 8" vert but, a trans cooler is a must. I run a rmvb cheetah and LOVE shifting on the street. One thing that I`ve learned over the years is that a HARD shift is bad but a good solid FIRM shift is where it`s at..........Trans-go valve bodies gave a bang shift instead of a firm shift my cheetah gives.