In general...
HKS and gapped to 0,02" is often needed. With 1,5 bar some times cylinder pressure can be higher than the high fuel pressure and will then light out spark. It will push back ignition also.
ECU need to have a scaled HPFP Map that reach beyond stock. Otherwise Fuel pressure will be the same as lower boost as the map will go in the roof.
So ignition and good fuel is very important as is the high fuel pressure. I know that Lap3 ECU is scaled good as it go along with the higher boost and also that trims then stay in range.
It is so that our cars is often faster at under 1,5 bar of boost so dont just go for the boost. Also backpressure at higher boost kills all upper rpm power.