Given that our subject engine has forged pistons and rods, but a cast crank, we figured we could safely go as high as a 200hp shot. It sounded anything but safe when the engine started missing on that particular run, so we shut it down and broke out the leakdown tester. Everything checked out OK, but our test time was over. The culprit turned out to be a loose rocker-arm adjusting nut. We'll have to try the big shot another time.