Just installed headers on my ZHP. Why did I wait so long to do this mod? Holy moly did it make a huge difference. Granted, I had clogged cats so the gains were larger than would be with a normal car, but wow does it pull HARD with the 3.46 gears. 2nd is just a monster gear. Never had traction control come on and cut power while in the middle of 2nd before. Car is a beast. Can't wait to Eurocharge it for even more POWA!