Ok quick question. Should I be able to hear the DISA flap open when I hit 4000 rpm - at the moment I can hear a definite click in the cabin when it opens. No problems with car otherwise - acceleration and idle all ok and no other rattling from Disa - but I can definitely hear it when it opens. Should I be concerned or is it normal? Car is an 07 e86 with 85k on the clock