You say that its fine just running from 3000rpm to 8000rpm at 8 psi but as soon as it the dyno puts load on the new donk missfires. You also say that you got bright fat spark even over a large gap (and the positive hurts when touched I ALSO KNOW YOUR PAIN - OUCH EEY MUMMA). Hows your fuel delivery system? its not missfiring due to running lean when loaded up or is the computer overcompensating when loaded and putting in too much fuel. If you can hook up a inline fuel pressure gauge near the fuel reg you could see if pressure drops/rises when loaded up. Can also watch the exhaust for excessive black smoke. But in saying that the dyno should be able to pick this up. It is quite possible for the coils to lack punch with crap loads of fuel/air in the chamber so your 4 bosch coil idea will eliminate that possible course. Let us know how you go.