Although I wanted to paint the Battlewagon in Bad Moonz yellow, I also wanted to represent the 'Red Paint Job' upgrade, so I am going with the red flames. I am painting the flames freehand and I think they are turning out ok. They are not easy to paint. IMO, the ones on top turned out better than the ones on the side.
Note - I am not sure why there is such a color difference between the two pictures. They were taken at the same time. The first picture (the side view) is the more accurate one.