ok i bought a 90cc atv (xtreme w/gy6) with a blown motor for my son. i purchased a brand new 150 gy6 from ebay and installed it. it runs good but i was told i should upgrade the exhaust. does anyone know of an exhaust system that would fit right up to the 90cc frame without being modified? or does anyone have a suggestion of an easy solution to this. Also i left the original cdi box hooked up because the new box seemed to have a little bit of difference in the clips,will this make a difference in the motors performance? If anyone had some advice to get the most out of this little atv (with in reason) I would like to hear it!!!