Of all the smoke & flame effects I've tried and seen others try, this's certainly one of the better ones... The only thing I'd add would be a camera trick rather than a modeling tip... I'm gonna try your technique and add a bit UV red, yellow & orange paint into strategic places (especially the flame-thrower stream) and give it some black light...
In the past, I've succesful with muzzle flashes using grain-of-rice/grain-of-wheat bulbs wrapped in spun glass thread (more commonly known as "Angel Hair") but the stuff ain't easy to find... My last batch was a small ball of the stuff that I pulled out of a broken "Angel", a Christmas tree-topper about 20 years ago...
Dunno why I saved it (I didn't think about muzzle flashes at the time), but as you know, a scratchbuilder never throws ANYTHING away until after it's been thoughly examined and salvaged, lol...