One of the best solvents for carbon is water.
You're never going to keep them clean though, exhaust is a by product of combustion, you ever look into a chimney, and see one that's clean? Even a natural gas furnace gets carbon in them, and it burns much cleaner than gasoline in a ICE.
__________________
Brad Yost
1973 T/A (SOLD)
2005 GTO
1984 Grand Prix
100% Pontiacs in my driveway!!! What's in your driveway?
If you don't take some of the RACETRACK home with you, Ya got cheated 
  
|