If its locked up there is no slip on the converter.If you're on a Dynojet with a stock converter you're probably near 16% loss so..
280hp÷.84 = 333hp
365tq÷.84 = 434tq
That's pretty good for 17psi etc, you tune and it's safe, then octane up for say 28psi & 18 timing you'll be happy.
Doubt they did that though
Its probably slipping away with low timing and no boost