The gray stuff is silicon wrapped over insulation. I thought insulating the pipe would be a nice touch but then I had a lot left over and just went all out. It actually came out flush with the hood.
The only thing I've noticed is that in first gear since I have an auto (
)when I floor it the engine will sometimes bounce off the rev limiter once or twice before it can shift. So either the engine revs faster or my tranny is going to shit.