Just got a full exhaust put in. Supplied my own headers and cat. Got a 2.25 mild steel made up for the rest of the piping.

Everything seems alright but whenever I rev to 2000rpm - 2500rpm it starts making this rattling/vibrating noise. I can't pinpoint exactly where it's coming from but it kinda sounds like from the middle or the back.

Should I take it back cause it's a bad exhaust install or does something need to set in after the install?