I just finished installing a set of slotted rotors and brakes on all 4 corners of my 04 STi. I only have 20,000 miles on them and the brake pads had a sufficient amout of material left on them. When I pulled off the stock rotors I noticed really deep grooves or lines on 3 of the 4 rotors. All of the markings were on the backside of the rotor. I contacted my friend who works at Mitsubishi and he told me that the EVO's with the brembo brakes were doing the same thing and that he has replaced the pads and rotors on several cars. I know that this definitely is not normal. Has anyone else noticed this on there own cars? The only thing that I can think of that might cause this problem is the stock brakes pads are too aggressive for the rotors. Give me some feedback.