I recently added a 50inch led light bar to my 2000 Ford F150 with door jam brackets, and also added a flowmaster super 44 muffer by cutting out the old muffler and putting this one in its place, but I'm having major vibration issues in the cab. From 40 to 70 mph my rear view mirror shakes horribly and you can feel it if you put your hand on the windshield. I don't know which one would be causing this, and I didn't have the issue before installed theses two things, anybody have the same issue or can help me, that would be great!

 

I hope you didn't solidly mount the muffler to any part of the frame or the body.
there is rubber in exhaust hangers for a reason

 

I don't have anything holding it up would that be my issue?

 

I'd slide under there and see if the exhaust is touching any part of the frame or body.

 

I did check my exahust, took off my light bar and taking off my light bar fixed the issue, just need to find a way to reinforce the brackets

 

Glad you figured it out.