As always I do relevant searches and read most post before posting myself.

As reading post regarding standard boost they usually run at 1.5 bar which equates to 21 psi.

I purchased my octy a month ago which has turned out to be a pain in the behind since.

It's got a list of mods..forge front mount, blue flame full exhaust Inc sports/decat, large forge tip, abd intake. Map etc.

no idea how accurate my boost gauge is but full boost it runs 15psi which equates to 1.03 bar.

what psi/bar should I be producing with the modifications I'm running?

My manifold is cracked and ****ing out the gasket. Will this be the issue?

Or am I adding this to my list to do in hunting down another issue?!

Thought standard was 10-11 psi? Stage 1 map would be requesting between 15 and 20 depending on map, mine requests about 18. 15 sounds low for what you're running, but what's being requested?

if there is any kind of exhaust gas leak before the turbo then this will reduce the boost output, In effect it's the same this as having the wastegate open on the turbo.

if I recall standard boost is around 12psi on those and around 20 ish when on stage 1 map.. What pressure does it boost at with the n75 unplugged?

Yeah that cracking isn't good news. At least you may have pinpointed an issue easily!

I'm sure there's no n75 or as spec sheet says n75j valve. There's no plastic section on top of the block.

Yeah it's a hefty leak out the manifold. Sounds awful and can feel a good amount of blowing when placing hand down to feel. I'll try add a photo.

I've got a new manifold gaskets etc that will be put on this week.

Crack plus blow at gasket

Crack

Looks like the crack goes all the way around the manifold

Standard boost is 0.6 bar, around 8.7 psi. You will have an N75 valve; it'll be poking out of the intake pipe and has three vacuum lines going to/from it. Unplug it and go for a drive to see what the boost is doing. And nice cracked manifold by the way. That must sound pretty horrific! Wonder if your setup is creating too much heat to be causing such damage. They normally crack around the turbo mounting flange.

Sounds like a bag full of bolts nails and fats. I shall do that tomorrow and see what sort of boost etc it's getting

Unplugged the n75 and boost was at 5 psi. I can only assume it's the major leak out the manifold etc. If it's still running low boost once it's changed think more investigation is required

That's probably about right for just actuator pressure and no N75 assistance. Get the manifold changed before you do any more digging around.

Exactly right mankee, the ko3 turbochargers normally have a 5pi cracking pressure on the wastegate.

at least he has proven the actuator preload is set correctly now... ive had a dig round my stash and i dont have a spare manifold here now, i must have chucked it, there is plenty of them on ebay, try and get one from a golf anniversary model if you can, they have a seperate chambers which only feed from 2 cylinders each which creates a pseudo split pulse setup for quicker spooling.

Knew I should of asked which other fitted I've already sorced a standard jobby for 50 quid. Would it be worth looking into the above if any are available and using that?

Got all new gaskets. Nuts and bolts will be ordered tomorrow. Think a friend is changing it Thursday. As much as I'd do it myself I feel it's a job for someone who knows exactly what he's doing

No its not a big deal which manifold you use, just use whatever you have. Its not a pleasant job replacing the turbo, the manifold is much easier though.

Sound job. Will give it a scrape and block. Me mates got a spare slot at his garage so might as well take advantage of it. Hopefully after that I have better boost. And can start enjoying the motor