I have a 2007 Coupe and there is a LOT of noise coming from the rear end of the car. Not sure if it is from the differential or if anyone knows what it might be. It is a roar that gets louder as speed is increased.

 

It actually could be your tires.
Had a lady friend drop by a couple of years ago with the same complaint, I drove her coupe and could have sworn it was the diff.
I jacked it up by the pumpkin and spun it up, no noise.
She got new tires and problem solved.

 

My car was noisy when I got it and new tires solved the problem. It could also be the rear wheel bearings or the shafts. There is probably less chance it is the differential.
If the tires have a saw tooth wear pattern or something similar it may well be the tires. Internal tire damage also makes a noise as well.

 

I just went through this. In my case the left parking brake return spring had come loose and was trapped between the rotor and drum and made an awful noise. Discovered this after purchasing a replacement diff.