The engine you are looking at in
this project of mine is a 27,2 ccm Stiga weedwhacker-engine
It turned into a screamer just by changing the carb(had to build a new inlet manifold though), and i have yet to try it with the tune pipe. I have used the same pipe on antoher car i have built with a 44 ccm Jonsered chainsaw-engine. It has a huge amount of torque.
So go ahead, i will follow your project closely!