My brakes are driving me crazy! They squeak like an old lady's LTD. I replaced the front pads last fall, so I guess the rear ones need to be changed now. However, I though about upgrading to drilled & slotted rotors at the same time, since I bought the 18's. The added weight may need a little help. Here's the question, with new rotors, do I need new calipers as well, or can I use my stock ones? Any help is appreciated.