If you are going to get a header get a high quality one like a Downey, LCE or Doug Thorley. I have a Thorley (which I believe is the cheepest of the 3) and i have not had any problems with it. Power wise is makes a huge difference. When i put on 31's my truck would not pull 5th gear but with the header, 2 1/4" exhaust with a turbo muffler it will pull 33's with no problem. As far as I am concerned a header is right up there with aggressive tires and diff lockers when it comes to mods that should be done.