When I got the bike this summer, the TT pipes had short mufflers welded on the ends. They were rattling so I cut them off and added 8 1/2" baffle inserts into the pipes to be a good neighbor. But I noticed afterward that I had lost power in the upper rpm range. I could hardly keep the bike at 75 mph on an uphill grade.
I removed the baffles this weekend and OH, BABY! When the motor hits about 5000 rpm, it takes off! It's not that much louder either. The low end power doesn't seem to be that much less. The bike is stock otherwise with standard jets in the carburetor.