There are many people that do track days on Ultimates so I guess that HPX should be just as good for mainly street driving. What I'm thinking of doing is get a pair of slotted discs and pair of A1RMs and use them just for track, while using my normal discs and pads (currently have A1RM but will change them to HPX next time I need to) for normal street duties.
I don't know what would happen to discs if I just changed the pads and kept the same discs for both track and street. Can anyone comment?

Adi