hey that looks like an evo 5 ms sleeve. aniwae to remove the carbon build up, i personally use autosol making that brass reaaaaaaaaal shiny. if u have the dremel with a polishing or buffing bit. heh. but buffing is for plastics i think =X polishing bit most probably. BUT be careful with those ports. nvr leave ani autosol in the ports or they will go up into the combustion chamber and reduce ur pinch bit by bit. heh.