Collinite No. 850. It's a very fine grit metal polish and wax all in one. Very inexpensive, goes on then right off before it dries, and leaves a wax on the metal that allows a quick wipe with a cloth for months later to remove 99% of any exhaust residue. My polished APR tips look brand new with no scratches using this for years.
Like a surgeon with a scalpel, my S4 is a precision instrument, with which I carve and dissect my way through traffic.
2010 S4 Prem+, Quartz Gray, S-tronic, Sport Diff, B&O, Nav, Gray Birch
StopTech ST-60 BBK - Stratmosphere intake - APR Stage 1 + exhaust
**** Have USB HEX-CAN Vag-Com cable if you need someone local to mod you ****