It's not that tricky... I just rubbed mine back with some of that green brillo pad stuff to get rid of the corrosion buildup, then wax and grease remover, then sprayed it with wrinkle black according to the directions on the back... Then hit it with the heat gun for a few minutes... keeping the heat nice and even.... it'll take a while, but pretty suddenly it'll reach the dryness point where it starts to wrinkle... you'll see it spread over the surface as you move the gun around.
Before:
Painted:
After:
I also did the crossover pipe, BOV and R34 strut brace in black wrinkle... and the exhaust manifold head shield in high temp black as well. Came together really nicely, looks clean and still looks almost stock until you put it next to a real stock car