i am looking to mod my truck a little bit, and i want to put a cam in, and put gears in . what cam should i get and where could i get some good front and rear gears? i have a 03 ext. z71 with the 5.3. and how do i tell what gears i have stock in it at them moment? also would a throttle body spacer make that much difference, i have not got a tune or programmer yet. i also have true flowmaster dual exhaust, i am thinking about going to a single inlet and double outlet magnaflow exhaust. should that help out on some torque since i have 33" tires?. I am also thinking about getting some firestone air bags on the rear, is it gonna matter since i have a 4" rancho lift?