Max pressure read with a manual gauge per the ATSG book and GM ESI FSM's is around 173psi. Not that I had some max line pressure issues on a car once, so we'll just pretend I did a lot of reading up on it. Some of us happen to have a manual test gauge for oil and trans pressure.Awesome tool when you have a question.
I can see both sides of the disagreement on the tuning. Do your best to keep the warranty, but tell him to eat it on abusive driving. A GXP with abusive driving is capable of crapping out a trans super fast. He is unfortunately unhappy about pulling everything apart for that forward band, sorry pressure still isn't to blame for that.
Did he test the soleniod for resistance? Most of them can be tested externally this way to gauge if there is an issue. This is one way of checking the internal harness and soleniod w/o opening the case back up.
