This gallery has some examples of the different flames that I have used with other photographs.
**Note** the colors are completely customizable to what you want.
Fiery Flame. It rocks. Nothing else needs to be said.
Flame is background color with a raised 3d look. The tips are reddish marron like the kart. The flames could have been like the flame on the kart, but in this case it kinda overpowered the kart.
Puple Flame.
Julie wanted the flame to come up from the bottom. Note the flame could have come from the side like the kart. This is completely customizable to your preference.