I swapped out my factory pads and rotors for hawk HP plus pads and stop-tec slotted rotors. It was a success for the most part. But I have a question it anyone is listening out there. When I took out the brembo pads, they had metal shims on the back. I wasn't sure if I needed to put those on the HP pads or if they were for the brembo pads only. I assume if the pads needed shims, they would come with them since they are specific for the year and make of my car. Anyone?