i have had the SOLO Mach x exhaust for about 6 months now, and i have had a rattle underneath the car every since. its not a daily driver or i would have really tried to find it by now, but its getting really annoying. It sounds like a metal on metal rattle, it doesnt do it constant, only at certain RPMS like around 2-4, when the exhaust sound is deepest, if im crusing and interstate speed and then just push the gas in 6th gear to make it louder and deeper sounding, also it does it when the car is parked and i rev it very little, just enough for the pipes and mufflers to have pressure on them to move. i checked the bolts on the hangers, they are tight. ive also read that someone took out their spare tire and jack and that didnt help, its definatly under the car seems like more toward the rear passenger side. is there ANYTHING i can check that could be rubbing against each other?