Hello i have piaggio nrg mc3 2004 i buy new giannelli extra pipe now when i fit it.. the acceleration is very slow... when i give up full trotle from stending i make a 6000-6500rpm and very very slow acceleration.. for 200m i make around 50km/h after that when it made 7500rpm it go very very fast.. and go around 11k rpm on a flat around 100+ km.h.. there is very much power but i want to make the start better and to have the same power in the low rpm like in the high rpm. the engine is stock...