RE: tuned pipe/standard muffler
J,
MAC (I think I got it right) makes a "tuned muffler" that kinda splits the difference in performance between tuned pipes and stock mufflers. They are black and about 8-10" long. They should have one for the plane/engine you want. PLus as a bonus, they are relatively quiet(er) than a true tuned pipe.
I use them on combat planes, and like them for the added performance.
Jay L.