Dual exhaust prob
 

On my car i had true dual super 44's put on about 3 months ago. I recently noticed the left pipe was hanging lower than the right so i checked under a noticed a hanger was broken. I took it to the shop I had them put on at and they said 2 of them had snapped. They welded them back and the next day i noticed everytime i hit even the slightest bump on the road, i hear a low pitch noise that sounds like the pipe is banging on something(hard to describe). Any ideas as to what this could be? the pipe doesnt seem to be loose now (gave it a check on the tip, havent looked under car yet). any help would be very appreciated :)

Check where the pipe bends above the axle. Sometimes when they raise the exhaust too high with the hangar the exhaust pipe rubs against the edge of the gas tank.

Yeah same with mine, it broke, and my friend welded it back on, but I'm not sure if I have that noise. Only because my mufflers are gone, like broken or whatever.

check where the pipe is closest to the gas tank but also check where the piping goes over the axle it may be rubbing or hitting against the frame of the car on the outside of the piping. If they welded the hangers, (which seems sort of odd considering a rubber hanger works better and is cheaper), than it may be hitting something. Just follow the piping to see where it is closest to anything else. Also check for marks which are a good indication that it is hitting something.