I recently installed a Weak-Ends exhaust on my Tomos ST. I put in a bigger main jet - 66 to replace the stock 55. It seems like I've gained a little power, but my top speed only went up from 25 mph to 27ish.
Today I messed around with the air/fuel mixture quite a bit, but it didn't seem to do much for my performance. According to the spreadsheet, there are people pushing 40 mph with just an exhaust upgrade and upjetting.
Any thoughts on why I'm not seeing much of an improvement? I weigh about 225. Maybe I need to stop eating so much pizza?