Car feel like it hits a wall at WOT

[drader]

Hey guys,
I just got my r32 gtst a while ago, it came with the wrong clutch so I put in a new clutch and just finished the break in period.
So i finally hit boost with the car and it hits a wall around 4000-4500, at WOT.
If I keep the gas pedal half way down it will boost like normal, but as soon as I put the pedal all the way to the floor it stops boosting and stutters and kicks a bit, but doesn't go anywhere fast. If I continue to hold the pedal down, the rpms will slowly go up but it feels like it is struggling to do so.

I have already looked for vacuum leaks with a propane torch, I couldn't find any.
I checked the sparkplugs, they are all pretty much new and gapped nicely.
I cleaned the MAF.
I reset the ECU.

Any suggestions?

[RWD_GTR]

i had exactly the same issue when i had a mad boost leak. my bov was leaking.

[aN4rk1]

I had the SAME thing in my car. it was a huge boost leak.

[DarkCaporaL]

Did you check the ECU for codes?

Could be air related, huge boost leak or your MAF may need to be resoldered. Try to borrow one and see if it helps.
Could be spark related, either coils or plugs...make sure your plugs are gapped to 0.8mm.
Could be fuel related, is your fuel pump keeping up with fuel pressure at WOT.

[drader]

So I tightened the screw on the top of the blow off valve all the way down, and it helped A LOT, but it is still not working 100%, so I am going to make a new gasket for where the bov bolts to the adapter plate, and we will see what happens!

[Matty]

Same issue here with a BOV leak. Tightened it up and good to go.

[vincegts]

i have this problem and i have stock waste gate and i cleaned the maf , and changed all the coils and i got new plugs

[archaeic_bloke]

might be far out guess, but just because it takes 30 seconds to do, have you checked the voltages on the Throttle Position Sensor? could just be that if they're off

[drader]

So i borrowed my friends working blow off valve and it fixed the problem.
Now it boosts properly and holds it around 10psi-ish.

BUT it it seems kinda laggy and slow, like it is a constant boost now, but the car is still slow.

[RWD_GTR]

fuel pump? thats my issue now.

[drader]

turns out it wasn't the bov, but my bov wasnt working 100% so it needed replacing anyways.
was backfiring/bucking/hesitating under full throttle, (stock boost)
so i put in a mbc, set as low as possible, (same as stock boost) and then it stopped backfiring/bucking/hesitating but was still slow
put in a 255 lph fuel pump and it is fast now.

fixed!

but i still dont understand how a mbc magically fixed the bucking

[SlidingSideways]

booo! i've been chasing this problem sine i got my 95 gtst... i just wanna make sure its nothing else before i replace the fuel pump..
assuming the car is completely stock, do i need anything else alone with the fuel pump? i.e. guages, fuel controller... or do i just chuck in a new fuel pump and giv'er? will my gas mileage be affectd much?