Not bad Chef, not bad! I would of personally had shadow on the checked area a little darker to give it a little more curved look and bottom part of the fire is really good but doesn't quite match up with the top flames on the visor.
Apart from that I think its a really good effort, not to many visible mistakes and has a really cool look to it, I think the blue flames are the best touch
.
and the carbon effect gets a thumbs up too
. good stuff.
I think the main thing is whether your friend is happy with it, and of course you are.