Hi out there

replaced the standard disk & pads on my 02 wrx bugeye about 5 mths ago with performance pads/discs, since then when i apply brakes they seem to be clicking or banging on i can hear it very loudly inside & outside it is now embarrassing can anyone help me to sort it???? cant work out what it is, was told by subaru that there is nothing u can do.... hmmm