Alyn @ AS Performance, Bob @ Aztec or Ian @ Godspeed Brakes will be able to sort you out.
I've got 4 pots too and personally find Godspeed's grooved discs excellent, i've got them hot enough on track to melt 2 sets of EBC bluestuff pads but the discs have resisted warping very well. I know his discs have a 12 month warranty against warping, even if abused on track.
Always meant change the pads if your changing disks too.
