Brake Grinding And Pop Sound?

[BriceW at webtv.net]

I installed new Mintex Red Box OEM street pads and Zimmerman cross
drilled and slotted rotors. The calipers looked and operated great.
I am still getting a kinda of grinding sound
at a slow stop.
I had thought that this sound would be history.
It is not at all nearly as bad as it was before the new pads and rotors.
Is this sound normal?
I have the G60 Girlings.
Everything was installed correctly and all surrounding things were
inspected and checked for integrity.
In the last week I have also heard an intermittent light pop after I
release the brake pedal after a spirited stop. I dont hear it after a
regular stop but only after stopping on some bumpy road going at least
40 MPH and it is intermittent. The sound comes from the front and seems
to eminate from directly under the brake pedal.