I just tuned a streetmate with the new Airsal 70cc Eurokit and the bigger jet that came with it. I drilled a hole in the exhaust just before the cat and junked the airbox in favor of a K&N style filter.
Goes like poop off a shovel. Fantastic acceleration and 50+-mph top speed. A mod well worth making. Am going to put a 21mm manual choke Dell Orto on it soon too. And I am going to change to a 28tooth front sprocket. The 21mm Dell Orto will fit into the rubber manifold if use a little elbow grease. Makes a huge difference along with a good expansion chamber coupled with the Airsal.