Meguiar's Hot Rims Mag & Aluminum Polish (damn, I sound like I'm shilling again, sorry)

I use this with a terry cloth towel on the outside of the Magnaflow tips, but for the inside I use the wool pad from our Headlight Restoration Kit, a corded drill, and the same Mag & Alum polish - a few seconds inside the exhaust tip and they're beautiful! Certainly the Mother's Power Ball (damn that thing, it's a great little invention and has made them a truckload of money!!) would be an equally good attachment for doing this, and their Mag & Alum polish is good stuff too.