i have a full built b16 with ~8-1 in comp
got it tuned to 1,5 bar and made 354whp.

when i drive it on 1,3bar 19psi i runs great all the way to 8500rpm
but when i have the pressure set at 1,5bar 22psi it starts to jerk @ 4500-6000rpm

the turbo is a garrett 57trim and the bov is a hks ssqv
the gap on the plugs are 0,02" and its bkr7e, the ignition system are in god shape
i tried to change the boost cut to 25psi but no change (Neptune rtp)
gm 3 bar mapsensor

havent checked the afr because it is snow here now, thought it could be very rich or something.

took the head of and the pistons look just fine,

could it be that i hit surgelimit just at that psi?

 

try to gap the plugs a little tighter and see what happens.