Low boost in 1st gear?

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I am currently in the market for another
turbo buick, so I have looked at a few in
the last week. The last car I drove, an 87
GN, did not run like I thought it should. It had
an aftermarket turbo, but the guy that owned the
car could not tell me what it was. The car was
set up w/ alky inj, different inj. (wide yellow
stripes at the top?, fuel pump, hot wire, big neck
I/C, THDP, and dual flowmaster exh. The highest
boost that I could get powerbraking it was about 3 lbs.
When I took off, the highest the boost would run
in 1 st was 10 lbs. When it shifted to 2 nd the
boost would immediately come up to 20 lbs.
I checked to see that the alky was not coming on too
early, and it seemed ok. Oh BTW, he also said
that this car had a high stall converter, but I really
don't think that it did. One thing that made me think
it didn't was the fact that at light throttle, the car shifted
so hard that it would chirp the tires. And I mean at LIGHT
throttle. Any vehicle that I had driven in the past that
had a high stall would soften up the shifts at light
throttle, even with a very aggressive shift kit. Any ideas
on the low boost problem? Thanks for any input!!!

 

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Anybody have any ideas? It acts like a very bad lag problem,
as the boost is gradually building in 1 st gear to a max of 10
psi. Is the problem just way too much turbo for the combo, or
is there any mechanical problems that may cause the slow
boost response? Any theories? Thanks for any input.

 

[BLACK6PACK]

converter my not be a good match or an exhaust leak before the turbo. Look on the drivers side header. I think all of them crack and need to be rewelded.