I suppose it depends on what type of paint (Taimya, acrylics, enamels, etc.) you are hoping to use. Tamiya's smoke does a nice job on exhaust, as does thin layers of Alclad's jet exhaust. I think even model master does an exhaust color, though I find it a little 'gold' to my taste. A heavier pre shade in the area might help before a layer of exhaust over top, but that could be tricky to accomplish the right look.