When I put a Mac's one piece on my ST 34, I lost some power.... The once piece is not intended to increase power..... If you need a little more snort, go with a
mousse can muffler.... Or a tuned pipe.
On my TT 46, I used a Tower 46 muffler which is sorta like a ultra trust muffler, but a lot less expensive... that was good for about 600 rpm over the Mac's one piece!!! I'm making a mousse can muffler for it now.. I think it will be better yet!!