The 6 heat range is for standard cars. The 7 range is better for remapped cars, whereas the 7 range in 'copper' are better for our cars but need changing every 5000 miles.
But most folk get the platinum 7 range as they last hell of a lot longer than the 7 coppers, but you compromise on performance. Me? I would have the coppers but can't be assed with the changing schedules. So the platinums won.
Sent from my iPhone when I should be working....