defiance

around 2 month ago i got dual flowmasters on my mustang and a few weeks ago i got a vibration at 1500 rpms. Does not matter what speed or gear as long as im at 1500 rpms i get a pretty bad vibration. The car does not do it in park or neutral. So i had the muffler shop put my stock exhaust back on, hoping it would fix the problem, but it did not. I got under it to look and it seems like the vibration is originating from the muffler and traveling down the exhaust pipe. I might be wrong.

I need help with this issue. Any ideas or suggestions?

rl05mustang

It sounds like it driveshaft related since it happens at the same RPM regardless of speed or gear the car is in. It could either be the driveshaft is out of balance or the u-joints tightened up. Take it to a qualified driveshaft repair shop and have them check it.