Timing tables can be used as a guide only, if u give people a timing table to run and it pops the engine it can be pointed to u.
Exhaust and intake restrictions can cause low power due to being knock limited, but once the restiction is resolved more timing/power can be made.
I understand what ur trying to do but tread lightly with it.
Q. The low powered G3, did they try dropping the exhaust to check for a restriction? What else was done to diagnose the low power? Did they try a much lower boost ?