I drive a lot on the highway with mine and when I go long distance in it I like to run about 90 mph, depending on the area it does it ok but I would love another 100hp/100ftlbs
I guess the stock bottom end can handle like 8 psi. I found this kit and with turbo, intercooler, and Accel Fuel Management you can run an additional 150 Horsepower. http://www.shop.505performance.com/product.sc?productId=1&categoryId=15. I never thought that you could do that with a 4.0... but with a price tag of 5 grand, I think I will make my own kit.