You don't have to go back to stock, but a 3.6 would probably help with the KR a little... Biggest mod is the foot mod, lol, stay off the gas and you won't hae KR, lolz



But out if you wanna go hard, try some Torco Fuel, or E85 to change the octane (higher), I read somewhere there's a ration you can mix (E85+95) without any major mods, haven't done it myself, but use the search function and look it up.

Have Fun...