Idk what happened. I was on the highway heard this gravel like sound, thought it was a bit odd yenno but didn’t care too much and then i got home and the noise was still happening on idle. I took some videos I’m hoping one of you guys can help me out. Got my exhaust done yesterday it’s been about 27 hours. Noises just started happening

 

Hard to tell with such a short sample and someone speaking. Almost sounds like an exhaust leak. Near what location of the car was it taken?

 

I posted two videos does the first one work? Did it through my phone. The sound is right under the drivers seat
sounds like gravel or something is stuck somewhere and rattling around in my exhaust.

 

Sounds like something is just loose. Head back to the exhaust shop and just leave the car running while it's on the lift. I had a screw loose that made noise and a bracket broke on the left side but it sounded like it was coming from the right side. All it takes is just a little vibration to make a loud noise. They probably knocked something loose when taking your muffler off. It happens.