How did you arrive at the pressures you are running now? Do you mark the tires for rollover? How does it drive - understeer/neutral/over?
It's hard to say what the changes would be without driving it. I don't have any experience with a welded diff, I just figured such a major change would effect pressures.

I autocross my prelude, which is not only open diff'ed but a FWD. I run in STS, though the only modification I've done at this point is wheels.

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1984 300TD