Here is a link to an FAQ from the StopTech Website giving part numbers from various manufacturers who have pads that fit our ST-40 calipers:
http://www.stoptech.com/faq/data/faq19.html
Also, there are pads available from Carbotech and Cobalt Friction that fit our calipers, either company can provide you with the proper part numbers. There may be others as well.
We have had different levels of success from various pads, the main variable being the driving environment, level of vehicle performance and driving style. For on track performance we've seen PFC, Pagid, Hawk and Cobalt show good results. On the street, AXXIS Ultimate, Hawk HPS and HP Plus all work pretty well.
Now the big question... What can be used on the street and track? Unfortunately, there's no pad we're yet aware of that will do everything on the track and street. Actually, the Brakeman #3 is probably about as middle of the road as you'll get, but it won't stand up to aggressive track use as well as other pads and it will be noisy and dusty on the street. If you choose to leave track pads in on the street, you may have cold stopping issues and increased rotor wear in some cases. Also, you'll need to keep them bedded in more aggressively than a street pad.
The best solution is to swap pads for track events. Yeah, it's a hassle and you have to figure out how and where to bed them in each time you swap. The plus side is when you're spending all that money on track rental, tires, fuel, hotel bills, feeding your crew, getting the suspension set for the track etc., you'll not be worrying about your brakes, you'll be concentrating on all the other aspects of going faster. Also be aware that some pads (PFC in particular) don't like to share the rotor, meaning they are not so easy to re-bed with different pads. If one had the means, they would have a spare pair of rotors and hats and swap them with the pads.
I hope this helps rather than confuses. If you have any questions, please let me know.
Matt Weiss
StopTech
mweiss@stoptech.com