Pulsating/thumping noise from rear when applying brake
 

I recently just had Hawk performance brake pads installed. When braking hard, there is a somewhat loud pulsating, thumping noise coming from the rear. It doesn't seem very loud since I only hear it when the music is not on. The noise comes at around 2 to 3 per second. Is it the abs kicking in? I wonder if I have too much rear brake bias. My rear pads I notice had a lot more wear than my front. When I replaced my pads, the front still had around 7mm while the rear only had around 2 - 3 mm left.

It does not sound like metal to metal contact. It's more like the noise you hear when you have a tire going down. I wonder if the Hawk brake pads do not work well with stock rotor.