Thanks Yard,

I will be putting two of these engines in an F7F Tigercat and I want any performance edge that I can get. Noise is not an issue where we fly, and the cowl is large enough to fit even the stock muffler.
I have never used the stock mufflers before, because I never had room to fit them in the cowl. I always used the B&B because they were so slim. I appreciate your lengthy response.

Jerry