I have a steggi stage V ported throttle body and eaton and a 2.8 upper, a SCT tune and no other supporting mods, which dynoed at 510/477. I want to change the pulley set up to get more torqe. Do i just need to add a 4# lower, or do i need the idler set, tensioner, etc. I would like to get all new stuff and want to do it right. Any suggestions??