I have been using Hawk HPS, their performance street pad since January 2006. A noticeable improvement over the Subaru OEM pads, but nothing drastic. They do not dust much and are rather quiet.
I installed the HP Plus autocross / track pads three weeks ago primarily for a track day I attended back on 9/21. They performed very well on the track, with no discernible fade and provided predictable bite on the 2004 OEM calipers (a tad weak by 2006+ WRX standards) using DBA 4000 series rotors.
So how are they on the street? The initial bedding process was much different than the HPS. Following the recommendations from Hawk, I found the HP Plus were far less aromatic than the HPS pads were.
HP Plus pedal feel: they bite much harder and sooner than the HPS. The pedal feel is quite firm and nearly immediate. The HPS are easier to modulate for smoother stops. A passenger in the HP Plus shod WRX might now think I’m too twitchy on the brakes compared to OEM. I’ve gotten used to the sudden bite, but cannot seem to stop as smoothly as OEM or HPS. For a performance car this seems appropriate.
I was somewhat disappointed when I installed stainless steel brake lines back in 2006, thinking they would significantly firm up the pedal feel. It was noticeable, but somewhat lacking. The HP Plus pads firmed up the pedal feel much more than the lines did.
HP Plus noise: yes … they are easily the noisiest brakes I’ve ever used. I have poor high frequency hearing. Any sound 9 KHz and over is difficult or impossible for me to hear. If I have my windows down and happen to be near a substantial vertical surface I can hear the squeal. I’m sure the drivers with normal hearing around me are entertained by the noise.
HP Plus dusting: not as bad as I was expecting, but the difference is easily noticed. It might be about twice the dusting of the HPS.