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Not sure on the pressure required to open the wastegate, but if you have an accurate boost gauge you could see the maximum boost being reached and that would translate to the wastegate spring?

My Link ECU and Boost Gauge confirm that I have a 9p wastegate spring.

J

THE REAL BORIS wrote:On page 01-13-13 of the 2004 Workshop Manual ..........

"Specification
65-70 kPa {0.67-0.71 kg/cm2, 9.5-10.1 psi}"

Is this the pressure required to fully open the wastegate?

The simplest way to find wastegate pressure would be to run the wastegate can straight to the signal source on a car that is not modified.

Can you adapt an actuator from a different turbo? Garret sell different pressure actuators. The stock Garret actuator for my turbo is about 6 PSI, but they also sell an 8 PSI actuator and some come with adjustable rod lengths. I guess the opening characteristics of each actuator might be set up differently to suit that particular turbo design though. So using a different brand may change the way the turbo comes onto boost? The actuator on the SP was shimmed to bump up the boost. I guess the SE one wasn't otherwise you would have taken the shims out already to drop the boost a little.

THE REAL BORIS wrote:It shouldn't matter if it's modified or not should it?

Yes it does,

The stock car produces 7.5 psi and a modified (breathing mods only) produces 10 psi with the signal hooked to the can on both cars.

What is that saying?

That the wastegate has started to open on the stock car and is fully opened on the modified car. (Answers your original question)

Unfortuantly for the modified car the fully opened wastegate is now not able to flow enough exhaust to bypass the housing via the wastegate which brings about creep.

Basically you cannot set boost below X boost (9.5-10psi in our case), without reworking the wastegate or restricting gas.

You could try another actuator, however looking at the yanks internal porting or an external wastegate appears to works best.

I have taken Blackster's tip and filled my air box with towelling to restrict air flow just enough to control things.

I dont remember saying restrict the air box with towels. But hey, whatever works for you.

If you are using a manual boost controller, you are fooling the wastegate anyway so I don't see how it will make any difference. Don't manual boost controllers bleed boost off prior to the wastegate to fool it into spooling higher psi before it bleeds boost off. Don't forget that the wastegate would gradually open from a lower boost level also controlling spoolup.