The nice thing about the 2300 is the 1.1L motor can get full advertised HP at 2600 RPM (less noise). The other brand with a .9L motor has to run 3200 RPM to get advertised HP. What I am getting at is our motors are idling compared to them. The high speed stop is sealed and looks to have a lot more travel and would void any warranty you have. I would think this motor is capable of more power at a higher RPM since it doesn't seem to drop off at full speed. That would be the first thing to try, and cheep compared to changing thing like injectors, pump, motor work, elec. fan instead of engine driven fan, turbo or blower. Removing the muffler and changing the air cleaner is not worth the problems. You could be the Guinea Pig.
Have fun
Doug