Hondabicycle from motorbicycling.com claims to have an exhaust mod that will make your 2-stroke engine more like a Harley. I'm pretty skeptical, but it's a fairly inexpensive mod. It involves creating an muffler end cap with two baffles and exit holes. The muffler is also packed with fiberglass. If anything, this will at least quiet down your bike if it's loud.
This mod could probably be achieved more easily in combination with my washer end cap mod. Since that has been proven to be an easy and superior end-cap, you could drill two holes in the washer and make your own baffle tubes. Then just JB Weld them in. Let that JB Weld set for a long time before use!
EDIT: Let's be clear that I have never actually tried this, so I have not verified if this mod does what it claims to do.