yeah peak torq is around 4 - 4.5 rpm
It's now fully out of my knowledge why its not happy with higher timing "people run 15+ in that area safe"
Fuel AFR is at 11s everything looks good on logs, sparkplugs are new "denso 1 step colder"
Only thing i can think of is lean it out a bit to 12s before 4500 and see if anything changes, to much fuel low timing can couse detonation?
Maybe Dom can add something