first of all dont pay for splitfires for $1000. buy them fron nungun for a cool $564 delievered to you door
i got mine 2 weeks ago... same thing is currently happening to me and i have stock engine aprat from boost to 10psi, front mount, full exhaust,filter and BOV,
when i hit boost around 4-5 to goes pap pap pap lags and then hit again...
but its not a smooth and quick delivery like most turbo cars should go...
but when i leave the car on 7psi its all fine no pap pap lagg...
i am also trying to find out the problem what i was thinking was maybe it was boost cut on the R34's or maybe my VTT is f**ked cause of the bad coils from before.
i have a apexi computer i want to put in and find out if it's the problem but not enough funds at the moment. BUT you have an apexi computer so i dont think there should be any fuel or boost cut. computer should have difused it...