I have a People 150. The carb, jetting and airbox are all stock. The ignition is stock except for a iridium spark plug. I have installed a NHRC exhaust system, a 1500rpm contra spring, and replaced the stock 15gram rollers with 13gram rollers. The scooter takes off great, then has a slight hesitation, then picks up again right up throught the power band. Top speed is a GPS verified 60mph. Scooter runs and starts great other than that hesitation. I believe the hesitation was there when new, but seems more pronounced with the mods I've made. Any suggestions?