I just went through all this stuff on semi-project car. Started and ran great, zero power, no boost.

Cleaned intake manifold + new gaskets
Fuel filters
Wastegate upgrade
Connected manifold pressure straight to the alda
EGR and flapper delete
2.5 inch straight pipe

14 peak PSI, spins the tires off the line.

The one thing the really helped was the bypassing of all the stuff controlling the ALDA. It came alive. I'm still going to adjust it and get some more off the line responsiveness, but for now, it's actually fun to drive.

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1990 2.5T 300D: 3 inch exhaust, GSXR mod, custom intake, egr and alda delete