As the title suggests, When accelerating from about 2000rpm to red-line in 3rd the boost will rise good and hit max (9psi) at around 2800rpm that's when the waste gate is opening (turbosmart boost tee) but by the time I'm getting to 4000 the pressure is dropping off and by 5000 she is down to around 5 or 6 psi.
I had to take the ball and spring out of the boost tee also as the wastegate was not opening at all with it in their (overboost ).
Oh and the wastegate is plumbed correctly and getting pressure from close to the compressor wheel.
Any idea's guys?

What does it run like without controller ??
Could be a restriction in exhaust ??

Without the controller the wastegate opens at about 2psi and will boost to around 7. Its has a 7psi spring. I'm thinking that the turbo maybe too small, it came off a 5.8L 6cyl truck engine. I don't think it would be exhaust restriction; its 2 1/2 straight through with 1 stainless muffler. The wastegate runs a screamer pipe also.

If your happy with the 7psi, then i would piss the tee controller off. If you want more boost, and obviously if the turbo can deliver it, then you need a proper boost controller. I had a 2 1/2" system, and it was choking, went to 3 inch and yeehaaa...........friggin sounds awesome too, IMHO.

I got a Profec SpecII, and it works perfectly. If i disconnect the hose to the top of the wastegate, and just let the gate control boost it gets to 7 psi and stays there. Check all hoses have clamps. I actually blew the map sensor hose off the manifold, but a couple cable ties fixed it. Could be losing pressure from intercooler pipework??? I'm sure you would have checked that.

We all want to do things as cheap as possible, but some things cant be skimped on.

Cheers

Daz

Where do you have the pipe to the top of the wastegate plumbed to? I was under the presumtion that they vent to atmosphere?

I think if you are using a tee to control then you bleed some of the pressure off to keep the gate closed. You could play with some light springs on the inside of the original gate to up the boost. The tee is probly the cause of the loss of boost. If you want a low budget boost controller, have a look on autospeed.com, search diy boost controller, apparently it worked well for about $100.

Cheers

Daz