Just noticed a slight grinding noise when braking so had a look and it appears I need new pads and one of the rotors is roughed up from the grinding. is it worth replacing all the rotors with an aftermarket sort or just that one... or does it even require it? Also what pads should I put in? just genuine ac Delco? figure if I can put some decent aftermarket rotors and pads in while it needs doing I might as well or are genuine pretty good?