My old school 340 upgrades and results.

It is pretty smooth at 4 and 5. 5200 on up it starts to shoot ducks. It will still Rev passed 6 just not clean. I am not even close to holding the pedal to the floor. I don't enjoy revving it so high in neutral with no load though. I will check the gap. I may try putting a vacuum Guage on it and hold it at 5500. If it was valves the needle should bounce.