I was wondering what pads people here are using for autocross/track days.

I generally only do 5-10 autocrosses and 1 or 2 track days a year, so I was hoping to find something that is more or less streetable. I ran both Axxis ultimates & Hawk HPS on my RX8 previously, and had no issues

Any suggestions on the mustang (its an 05 GT)?

 

Depends on what you want in a pad. I run Wilwood E pads on my 67, daily driven. Decent cold friction, but work better when warm. In normal driving they're relatively easy on rotors(as a high friction pad go) and they last a while. Wear is quite good for a pad of their capability. Peak brake friction comes in at around 500-600*F and slowly tapers off out to 1,000*F. At 1,000 they're still making more friction than when they're stone cold. They stop very well once you get them warmed up a bit, which usually only takes 1-2 hard brakes at moderate speed. If I have to panic stop on the freeway they're usually warmed up and gripping harder before I come to a stop. Work well at the drag strip, pull the car down from 110 pretty fast.

Drawbacks are they're more expensive than some pads(about $60 for a set of pads for 2 wheels now), make a fair bit of dust, and can be VERY noisy, especially when hot. For AutoX if you've been sitting for a while on a cool day then they will probably take a few turns before they get fully up to temp, but as far as stopping power the temp vs friction will mostly just effect your pedal effort, since they should still lock the tires either way.

That's what I run anyway, it just really depends on what you want. I run those pads because they'll take a ton of abuse and my rotors will be glowing bright yellow before those pads start to fail, great for high speed road courses though since you won't get fade and don't need to run radical cooling solutions for most street cars.

Generally, in a pad you want what gives you the best stopping power and pedal modulation without excessive wear or fade.