spark plugs and yes you can buy 0.8mm gapped plugs NGK coppers bcrp6es cost you f**k all and isn't dodgey
coil packs have probably had it as well,
stock ecu runs the engine pretty average at that boost pressure (very rich),
I also get flat spots (not missfire) up around the 5k mark with stock ecu & 10 psi,
I threw my un-tuned PFC in it and it ran perfect to the redline out of the box (tune coming soon)