We went from a 4.56 to a 5.14 and I was very surprised to pick up .250 with the exact same motor setup. We did not even pull the valve covers over the winter. I could run the quarter with the 4.56s but, no way with the 5.14s I shift at 6000 with a glide and cross the traps at 6550. 30 inch tires. One thing I forgot is I did make a ladder bar to go with the Slide-A-Link rear suspension and it did help the traction. So maybe that is where it is.