If the element from one of the others will fit in the Vortec set-up, try that, just to make sure it doesn't have a restricted (from dirt or re oiling) element.

As far as 'cones' make sure they are bellmouthed. Certain designs work better than others as not too make the air trip up. I'll check my notes and see if i can find designs of what I'm talking about.

Are you suggesting running the K&N element dry since it is in a boat?

No. I have seen the K&N's shrink by a good amt. In fact, I think I have one kicking around that shrunk by a bunch. Round style for carb's.

I see more damage done by cleaning and re-oiling. Myself included. I even set forth to learn ho to do it 'correctly' years back, and never got it right.

So, issue is, by the time it's time to clean, is really the time to huk it and replace it. Hard part, if not impossible for some arrestors, can be getting the element by itself.

Can you imagine how many of those old style Mercruiser Gen V flame arrestors have been pitched in the trash over the years. LOL. They are the best ones!

I wasnt even planning on testing one since i had a gutted out one done but consistently the completely stock one made 2 more hp than the gutted one so then I did all my testing with the stock one. Now. looking on web AZSM no longer sells the restrictive one, they now sell a re-branded vortech engineering version that is identical to the crockett/vortech one we tested. I DID find the crappy one on Hardins website, when AZSM sold them they made claims of gains, at least Hardin is honest and says it will NOT support over 500 hp and make NO mention of a hp gain! Keep this in mind, will not support over 500 hp doesnt mean it works perfect to that point, I will say as bad as it performed it becomes a mess much earlier!
http://www.hardin-marine.com/p-13296...-arrestor.aspx
Note: These clamp-on filter/flame arrestors have limitations to their air flow capability. The filter element can only support enough air flow for approximately 500 horsepower.

Courtesy of Gimme Fuel

Still didnt make as much hp as the stock genv but looks cool. Im going to make some cones to direct airflow for it and test it again

Makes sense. This is the one I have, and back to back with a stock Gen 6 FA, they were within 1 hp. But again, that's on stock motors that pulled only 438 hp.

Negligible on stock motors, but once you start flowing more air, they appear to become increasingly worse.

SB do you recommend not oiling when using a k&n?

Discard and replace instead of clean and oil. My 02.