[Wreckless]

Just spent an hour at my fabricator's shop. With just the simple drive down the street to the shop with the wastegate back on, the car made boost for the first time in years and ran much better. Once the car got up to temperature, it went to hell all over again.
So, since it's much better when cold and then gets terrible as it warms up, we're back to thinking it's engine management.

Just to make sure, we got the car up on a lift, and we even went through the pictures of the up-pipe fabrication that Sam did years ago.

Andy, my fabricator guy, showed me the up-pipe from a 410awhp 2005 STi that was on the other lift at his shop. The up-pipe was all of ~1.5in for the whole motor pre-turbo, and this car obviously makes the power.
The up-pipe and manifolding setup that is currently on the car is all 2.25 ID. Andy said that if he'd built the setup he honestly would have gone much smaller and that if anything, it was too big.

I'll be contacting LAS here and hopefully I can get that new 2v7 tune for the 370cc primaries - even if that's not the overall problem, that'll be a good thing to have once the car is back into shape.