I've run 4.10s in all of my Mustangs, and it adds so much to the car. My last set was also US Gear. Bought them off the web for like $150, and installed them myself. If a tune wasn't required for the install, I'd have done it already. Sadly, I'm going to have to wait in pain for at least a couple of years, or until I say screw it and just do it. I just can't justify tossing a 5-year warranty out the window...yet.
