The easiest way to improve it would be to drill out the allen bosses that run through the plenum and weld up the holes, I'd love to test this mod soon.
Good idear! For a long time, I have been considering sawing off the plenum of the 3B and making a tubular plenum with a front-facing TB. That, along with cleaning up the allen bosses, should be just fine.
I agree that if the turbo is out of its range there is nothing I can do to change that. What I was getting at was that by eliminating intake manifold restrictions, I could allow more boost to "reach" the intake by easing a bottleneck--eliminating backpressure between the compressor and the IM. I wanted the turbo to be able to reach its full limit instead of being stopped short of its limit due to restriction.
I just can't let myself dump the kind of money into this 4KQ that I had once planned, so I want to look for every little affordable trick I can do. I believe that, at 400HP, I can built a nice, low-stress, 2.6L 20V that should make excellent long-term power. I know that at that power level, the Eurovan parts are by no means necessary. But it's a street engine, so displacement would be nice. Plus, I'd like to see what the big bottom end will do to the torque and the shape of the horsepower curve. It should make a much more usable street engine, I think.