I've gone a step further to improve the low-end power in the bike: before wrapping the baffle, I added a flat disc (or a large washer of teh right diameter but with a tiny center hole) into the middle of the baffle. This I did by slicing open the baffle, inserting the washer, then [having it] welded it shut again. Then when wrapping the fiberglass on it, I left this section open so the exhaust would exit the baffle, then re-enter it, to get around the washer.
This was done originally because the locals gendarmes used to stick a 3-foot-long wood dowel up a bike's pipes if they stopped someone for a too-loud exhaust pipe(s) in town. It 'stopped the stick' and saved a ticket. It wasn't until we had done several of these that we realized it was also improving low-end torque. This practice started with straight-piped HD bikes and became part of the 2- and 4-cylinder bikes passing thru my shop after that 'discovery'.
...then I got an aircraft engine designer's book, which spent 3 exhaustive (sic) chapters on exhaust designs, written by the Brit who designed the legendary Merlin engines of WWII. That was (and still is) one of the most illuminating technical books I have ever seen! It is because of that experience that I seem to be in the minority when it comes to the question of "how to increase power with my pipes..." - I always have ideas quite different from others, most of them also proven to work.
