Thanks For all the input..   I guess I just really need to run it first to see what kind of numbers I get from it. Will post those numbers when I get them. as far as the Header pipe is concerned, I am probably going to put a Pitts style Muffler on it, since I am planning on using this engine in a 70" GP Revolver. I just don't think that plane would look right with a Tuned Pipe running down it's length! 

Anyways, Thanks again for the help and info, its greatly appreciated.

Craig.