Standard GTA Turbo boost gauge

How reliable is the standard, built-in turbo boost gauge in the GTA?
I realise that it it only really shows whether the turbo is doing anything or not and when it's over-boosting.

For the last few years, my boost gauge will only read up to about 60% when the turbo should be on full boost. Before that, it used to go up to the full end of the scale.
I've had the turbo investigated and the waste-gate actuator changed (there was a problem with my original actuator) and set up and apparently all is well. However, the gauge still indicates that I'm not getting full boost.

Has anyone had a similar experience? Should I believe the gauge and make sure the turbo is doing what's it's supposed to (with a proper gauge)?
Or is this what happens to the boost gauge over time and most likely all is well (as advised when the waste-gate actuator was setup) with the turbo?
Is there a clean-out of the vacuum-style hose to the sensor from the plenum that you can do (there is a constriction piece in that hose, though isn't there)?

Thanks very much for your help

Jon

The gauge is by no means a reference of correct level. On the sender (in the engine bay) there is an adustment screw to adjust the reading on the dash, hence why it can read anything.

Just buy a new aftermarket gauge for a true reading.

Thanks David. That clarifies the situation

I'd better add one of those to my shopping list!

I've finally fitted an accurate aftermarket boost gauge and gone out to get some readings.

On full boost, I'm getting a steady 9PSI and the gauge has captured a peak of about 9.5PSI.

Is this the standard (factory) amount of boost I should expect to see or is it down a bit? (I know the boost safety cut-out activates at 1Bar (~14.5PSI), which seems a long way from 9.5PSI

Thanks

Jon

9-10 is about right for standard pressure.

Thanks again, David. Puts my mind at rest.

Interesting that there's so much headroom before the safety cut out - or does that 4-5PSI get produced pretty quickly if you're wastegate actuator is a bit out?

Gives some room for careful tweaking with a bleed valve before hitting the safety, I guess.

The car runs 10 safetly, as at anything above this the standard turbo, intercooler and injectors are stretched past their limit.

Thanks again, David. Puts my mind at rest.

Interesting that there's so much headroom before the safety cut out - or does that 4-5PSI get produced pretty quickly if you're wastegate actuator is a bit out?

Gives some room for careful tweaking with a bleed valve before hitting the safety, I guess.

The 21 Turbo is set to cut out at about 19 psi, the standard car runs just under a bar. I run my car at 18 psi, its a shame the V6 ECU is so restrictive.