Several friends of mine went with the HPI 58MM. TB. I also went with it. I didn't dyno my bike because I'm running a Thundermax, and didn't want to spend the money. Everyone one that went with the TB loves it, they all noticed a huge low end response difference. I have a 117 and am looking for all the HP I can get out of it, I'm trying to get educated in Baffles, and size with performance increases, I have Rinehart tru-duals, and 31/2 pipes, so I'm looking to squeeze a little more HP out of the Exhaust system, will 2" baffles work, since I have the stock baffles in the pipes?