do a search. 4:10 gears, 80mph 5th gear 3000 rpm. A catback will give a little power, more sound, but worth it. if the silencer is still there yank it. You should notice a k&n. Computer programer. Gears freaked me out for months before I did them. Gotta say thats my vote. As far as gas mileage, driving 18 highway, sorta (more like 50 to 80 or faster)miles plus in town miles, I get around 220 miles out of a 1/4 tank of gas. And I definately have a heavy foot. or you could go off road with the exhaust. 300 catback, 150 for a hpipe ???????good luck, chris