I don't think that 32 mph is too much for the carburetor and jet. That's only 2mph more than with the stock exhaust. The carburetor is not so suddenly going to run out of fuel and starve the engine so it overheats because on an extra 2 mph.
If you were running closer to 36 or more MPH, there's a chance it was running lean due to inadequate carburation.
Im gonna suggest that you reinstall the stock exhaust until you get that carburetor straightened out. It's far more difficult to solve 3 or 4 problems at once than it is to start from scratch and work systematically, correct one thing at a time. The performance pipe just confuses things and may be adding it's own peculiar problems.
Then go to the Articles section in Resources (above) and find Fred's Guide and give the bike a tune-up. If you don't have a manual, go HERE and grab all the Puch manuals.. learn how to adjust cables, assemble the carb and other stuff.