I am in the same boat, been chasing leak/boost issue for last few weeks.
I have GH Intercooler
PPE Catted Downpipes
XDI Fuel pump
GH Tuned E40 and 93 tunes, many revisions back and forth with Matt.
My boost Command is 18PSI and it holds there for half of the RPM and than it starts to drop and I sendup at 12-13PSI by my 6K RPM with WG at 100% closed
5500RPM is where my PSI and WG cross, WG goes up PSI comes down.
I troubleshooted for ever, did multiple system pressure tests, you can find them in my videos: https://youtu.be/awUptqYTFVw
Did not find pressure leak, I replaced all clamps on my pipes low and high side, I retighten all bolts, checked blowoff valves few times, replaced boost controller, removed all pipes and inspected, I completely removed intake filter and ran without it, nope, did not fix it.
I checked WG, pressure tested it and it holds closed for long time, so that was crossed off of the list. I cleaned 3bar and mass flow sensors too.
I inspected my turbo fans/wheels and they look like new.
I have 31K miles on my car and I just don't believe they are tired turbos..
What I came to conclusion is these small turbos have their limits at high RPM engine demand, I say at about 5500-5800RPM its limits, Smaller turbos have more benefit at lower RPM, no boost lag, larger turbos are more efficient at higher.
Anyway, I just came to conclusion that I just shift at 5500 and call it good.
Here is my log view, 2 and 3rd gears pull, 3rd was not all the way to 6K, ran out of the road, LOL
Red is RPM, Blue WG, Green is Boost in PSI.
2nd gear (first spike) See how blue WG flattens 100% at 6K shift and boost is 12PSI
3rd gear (second spike) 5800RPM WG 100% flat, boost at 14PSI
Thoughts?
