When you installed the rear pads, did you put some type of silicone lubrication in the back sides of the pads? Also the grade of pads can can affect the quietness of your braking. I go with ceramic pads on pretty much any vehicle that has them available for choice. I'm also not too Keene on drilled performance rotors. They warp easily and aren't worth the extra money in my opinion. If those rotors are installed backwards, they'll make all kinds of noise.