people talk about improved transient response, but i think that's only for setups that are not being pushed hard. typical modded evo has pretty high turbine backpressure at full boost, and keeping the heat in the exhaust gas is only going to make the back pressure even higher.

 

I have coated a bunch of setups. but my coater is the best on the planet. he coats the inside as well as outside. there is a very noticeable tq increase after coating. less heat is lost to engine compartment. more heat available at turbine wheel.