i'm getting engine load based pinging

[camshaftgsxr]

yep.. it happens only when its hot and only when i'm loading the engine, it sounds very metallic, like a thin metal rod being shoved into a metal bladed fan, when the engine has been up to temp for a while it becomes more sensitive to engine load (beginning to ping at cruise and getting much more pronounced upon accel.)

i recently got a new exhaust installed (professionally) and all the welds are clean but could a crack in a header or a gasket cause a temp related leak?

i also switched to 87 octane fuel but the pinging DID NOT begin the same time i switched fuels it began a month afterwards.