I guess we differ in opinion gravy...
I find a properly tuned expansion chamber exhaust to the be THE BEST performance enhancement for a 2-stroke ever made.
I'm talk ~ 1/2 a HP increase.
It's like a reverse Turbo Charger and work like this...
If you want to see my pros and cons for 2-stroke performance enhancements look here.
http://kcsbikes.com/Performance.asp
Far from thorough but based on first hand knowledge over the years of building.
Hope it helps.