I raced all last year (local and national SCCA events) on stock pads/rotors. This year I will start with upgraded pads, haven't ran into an issue with autocross to upgrade rotors (although that is on my list).
I ran EBC Yellow pads on my SI when I raced that and I loved them. Probably will stick with EBC this time around also.
Going to run all PCA and majority of SCCA events. Including the two national events in July. Here is the post I made with all events listed:
http://www.ft86club.com/forums/showthread.php?t=54973