[decooney]

Try a 750 or up to 830, properly jetted and set up, with the right power valves, and see how much better it runs without an air cleaner first. Then get a bigger air cleaner.

I too thought my 9" K&N was big enough. Ran it for 2 years that way. Just switched out to a larger one again and it runs slightly better across the board from idle to higher rpms. I had a stellings before that and it was choking my motor off. I don't know if I believe those flow tests any longer.