ev·o·lu·t-x-tion - change in the genetic composition

[BrianG]

I'm not exactly a Nitro expert, but I do know that the header pipe length and diameter does make a difference. It would probably be better to extend the actual exhaust tip as long as it isn't restricting.

If you are concerned about heat from the pipe, what about fashioning a heat shield out of some 1/16" carbon fiber or similar material?

One thing I never liked about Nitro is the mess from the exhaust mixed with dust. It gets everywhere. That said, I would try to divert the exhaust as far outside the body as possible to keep things looking pretty.

Nice conversion BTW!