My vegas was the same way, I believe its the tune with the pipes, I had the K&N filter, stage one tune and the swept pipes with rpw baffles, and the plugs were very dark, black and sooty.
2012 Cross Country(Imp blue)
de-badged,(self tinted) Klockwerx flare, passenger backrest, passenger touring floorboards, VictoryHID kit, Miller Mufflers short baffles,Lloyds air filter(from witchdr.)Lloyds timing wheel(6*), adjustable drop link, cut seat, removed cats, PCV w/at.
1978(2009) Honda cb750 chopper