i hear a scraping noise when i apply the brakes, louder at lower speeds. its a metal to metal sound but what could be causing it?

I would guess worn pads. The wear tabs may be hitting the rotor which means it's time for new pads. Makes a lot of metal on metal noise. That would be the 1st thing I would check. Try these combos: Factory rotor with Axiss or Friction Tech pads. Powerstop X-drilled with factory pads. 2 nice setups.

Cossie