knocking at higer rpms

Is this common in the US? low octane fuel ? Im really surprised?! the LOWEST in Denmark / Sweden is 92 octane.. EVERYBODY runs 95 octane including me...

And then there is the premium Shell V-Power 99 octane...

And rarely you can buy some places 98 octane..

99 here is like av fuel for small aircraft
 
Your right on the edge of being to lean, when it gets hot it's detonating!, mine did this and I upped the main one size and it went away.

see for me thats not the issue i can richin it up so much you can even wind out in 6th gear and it still does it. i even took the head off and checked for signs of detonation and thier was absolutley none. thier would be signs of detonation if thats what it was. i just started having this problem out of the blue. mine is deffinitly an ignition issue.
 
umm...just throwing this out there...can't forget the small lil things...like a new head gasket?..i blew one of those and got a knocking sound only when in gear..when outta gear it wouldn't knock...it's kinda hard to see the air leak from it cause it's hard to get the smoke to come out of the botte of the head but it happend to me so throwing it out