I run a 428Sb with a 28x10 and 4.56 gears running high 9s.Shifting at 7500 and going though the traps at 8000. The car seems like its running out of steam. I was told by my engine builder to set the car up to run 7400 out the back door. That's where is made peak hp. I think i'm going to try a set of 4.10s