Those are some nice numbers. Unfortunately the power you achieved during your best run will not stay since your computer will adapt out the extra fuel you added by raising the fuel pressure. The upside is that you know that your engine will run better with a richer air/fuel ratio. You can get a chip burned or buy an SVO extender to tweak that so it stays.
Do you have a power graph that you can scan in and post?
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351W 89 Mustang GT Convertible