Some humming is caused by J-hooks or slotted discs - this is normal. If you have some squealing it's
caused by the pads.
I had humming with all my slotted discs (AP, Brembo, Tarox). A friend is running Pagid RS4-2 (blue)
on his Octavia RS with stock calipers (+ Tarox G88) and the pads are squealing like hell when cold.