I use a pro 5.0 with blue permatex gasket sealer and get a slight rattle at lower rpms. I have seen a gasket kit offered somewhere that would prob. take care of this .(Sorry dont remember where I ran across it.) But I Wouldnt be afraid to use any Steeda product on my 03'.
steeda triax is a decent shifter, better than stock. like 01 cobra said, since its used you need to make sure its for your type of trans. if its not go out and get a mgw, you'll thank yourself later.