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What you are describing sounds like boost creep. This does occur on the B6T to a point, especially with an upgraded downpipe. Best remedy is to port the wastegate to the size of a quarter.

Waste Gate Valve
1. Cool the engine.
2. Remove the waste gate actuator hose and attach
3. Adjust the compressed air pressure to 48.1-58.9
kPa (0.49-0.80 kg/cm2, 7.0-8.8 psi).
4. Check that the rod moves when disconnecting and
reconnecting the hose applying the compressed
air.
Caution
Do not apply compressed air higher than 98
kPa (1.0 kg/cm’, 14 psi).

wait wait wait...the If the B6-T is practiclly the same thing as the DOHC B6, how does running 8 PSI through the motor only add 27HP!??! 3-4 PSI sounds about right to me. Just an opinion...

Totally different CR ratios, different cam timing, intake manifolds, etc. Everything makes a difference.

There are a few more things that contribute to that small power gain...

B6T:

7.9:1 compression is LOW compared to the NA B6's which are some where around 9-9.5:1.

SMALL turbo generates a LOT of heat which the stock 323GTX Intercooler is BARELY able to cool sufficiently. The stock turbo cant pump more than 14-16psi before outlet air temps skyrocket causing easy detination.

Timeing gets retarded as boost pressure rises via a vacum line connected to the distributor which cause a mechanical vacum advance of the time. You lose more HP removeing timeing than just lowering boost and advancing timing.

Those are the main reasons for the small gain. The small intercooler and low compression are the biggest to killers of HP.

When I had the VJ-13 & then a VJ-13/14 hybrid turbo running stock wastegate pressure it ran at 9psi on my car. I had a MASSIVE front mount for that little turbo! My IC is commonly used on t3/to4e turbo Hondas making 400+ HP. I figured it would have lowered the boost but I guess APEXi wasn't kidding when they said ULTRA low pressure drop! As far as the waste gate opening a little early...you shouldn't notice it on a turbo that small cuz it spools soooooooo quick. It is actually a good thing to help PREVENT spikes (does still spike a little when rasied and ported). If you can actually notice that the gate is opening early then your dash pot may be damaged or probably just stuck partly open and not closed all the way. You'll have to remove the exhaust housing to check it! Or if you were to get it to me I could check it for ya, I also have some spare parts if it needed repair (replacing wheels requires spin balancing if you ever had to do it). I'm hoping to start my own shop soon, or at least on the side for fun, I'm hoplessly hooked!