Exhaust mods. help quite a bit I'm sure someones told about taking the gutts out of the muffler. I've run across to different styles one with the baffle screws on the side remove the screws and cut off the 1/2" pipe and reinstall it a little more noise but not bad. The other type has one screw on the bottom of the muffler right in the middle. Take it apart and saw off the long tube and reinstall an TADA more power and a little more noise. You can dab a small amount of sicilone where the muffler goes back together as it helps stop some of the ounburned oil streaks.
Another easy mod is remove the sparkplug and using a dremel cut the ground electrode to a v shape this uncovers the electrodes so the flame curnel is exposed better to the fuel mixture which permits better combustion of the fuel.
Another easy mod is raise compression remove the head and replace the stock gasket with a thinner one( home made) special material also
And I make my own pipes for the exhaust and my own boost bottles.
easy to do if you have a welder and lathe for the last two.
Norman