I had avid shorty-4s and the stock pads were HORRIBLE for squeal. After about 1200 miles I changed to kool-stop pads and that helped, but the braking power was never great and the squeal was still noticable.

I finally got tired of that and switched the front brake to a Shimano canti, and now braking power is up, as is modulation control and squeal is gone. The power thing was due to being able to select the appropriate length cross-cable (avid one was too long, so there was a big angle with little mech advantage). Anyway, I change pads at 900-1200 miles. I'm a big guy and have several hills that help grind through the pads quickly so you should probably get more life out of yours. (unless you + gear weigh in at about 250-275 lbs).