I think Kat 6 is already sold out,it was sold out within first 2 minutes.So the Kat 7 was released,as so far they only made 30 000 tickets available while the stadium holds about 60 000 for concerts.(I think,but I'm not sure that Kat 7 is upper north stand,above Kat 6) About 15-20k tickets are sold in first 2 days combined with presale.