hi ive got a piaggio diesis 100 (85cc 2stroke), the standard exhaust is crap and i wanted to replace with a a performance pipe but none are made for this engine had a look in the garage and found my pm tuning pipe off the nrg 70 i had. i managed to fit it with a bit of mods to the brackets. its now down on power. ive tried upjetted the carb and its worse than standard jet size. could the pipe be to restrictive for a 85?