I have a 6-spd manual Rubi Unlimited with a Kore 3.5" suspension lift and 35s. Stock muffler, no CAI, no chip. Most driving at 3000 - 7500 feet above sea level. The power is fine, although I don't expect to pull anything more than the occasional trailer. I won't beat the Audi sedan next to me off the line, but I'm not slowing traffic either. 6th gear only gets used at 70 mph on a level or downhill road. I have no plans to regear.