My brother's car just had an accident. Bodyshop install the muffler. Everything is allright except the gap between muffler tips and rear bumper are 0.50" bigger than original. It's not noticable, but his eyes catch it.

Any recommendation shop with good price to do this?

 

if it was an insurance claim, take it back to the place where you had it fixed. They're required (the insurance company) to return it to original specifications.