The bike is almost 10 years old. The XT brakes are pre-bled drop-in replacements for some Juicy Avids I suffered with for all these years. I also replaced the rotors with IceTechs. These are already a major improvement, but I was surprised the back brake seemed to have more immediate stopping power. I do a lot of my own disc brake work on my road bike, which has what are essentially XT brake calipers, icetech discs, and a different but functionally equivalent (ultegra) lever. So I am familiar with what can go wrong. I was just wondering if there was any inherent difference in feel with a 180 rotor vs. 160 mm rotor. (If anything, I would have expected it to feel like it had greater stopping power). I'll swap the pads around and see if that makes a difference.