I have autocrossed my '08 Speed 3 with both Hawk and Porterfield pads, and I have to say I'm now a loyal Porterfield man. The input actually came at a driving school when the instructor, a SCCA Autocross national champ, actually explained to me why I was struggling to get my braking points right. Below is the conversation we had after a frustrating few runs where things seemed to always be changing.
"What pads you running?"
me: "HPS with SS lines all around, super blue fluid".
"How consistent to the breaks feel to you?"
me: "They're super solid, but when I'm trying for that late breaking point, I can never seem to get the same result. The brakes are linear up to a point, and then they just seem to get random!"
"Exactly. The HPS are NOT linear. At the limit, they will both grab very hard some times, and other times not so hard, and it depends on how hot they are and a bunch of other factors. This is why you're too slow into some corners, and over cooking others."
I switched to Porterfield R4-S brakes and I LOVE them. They are so consistent, so linear. I was able to make my braking points so very consistent I was able to take my autocross times down because I was no longer trying to compensate for changing brake points.
The downside of the Porterfields? After about 20,000 miles, they have started to squeal. They still have plenty of pad left, but at light pedal input, they squeek a lot. I asked Porterfield about this, they said that brakes that are heated up (say at an autocross) will get hard and will squeal more, but still stop just as well.
