XJET,
This still does not answer my problem listed below:
On my Pitts Muffler it did have two 7/16" OD (3/8" id) so I plugged one and then opened it to 3/16" id and the other is still 3/8" id. Seems to run great now. ramps up rapidly. I am not sure whether it is causing harm to the engine or not. When I rev her up to full speed it smokes so I am assuming that it is not running lean and the exhaust is oily. I am not sure whether I really like these pitts setups or not!

If you could and know alot about pitts setups just email me directly.

Thanks,
Rick