I have one in my Duramax and it out performs the K&N hands down. I was considering going to a large cone style Green Filter for my 496 HO's... Anyone tried these and would it just clamp on in place of the stock Merc arrestor? I have a K&N made specifically for the 496, but found that it didn't flow anymore than the stock.

http://www.greenfilterusa.com/universal.asp

Are they CG approved?

Going to a K&N or other aftermarket flame arrestor on a marine motor is really just for better filtration. Most flame arrestors are about as free flowing as you can get. Even if you find something that does flow better, I'm sure the difference won't be enough to improve performance in any way that you could tell, except cleaner air. .

And Davem's question is also very valid, and I bet we know the answer. Green makes street stuff only, not marine (unless that's changed).

Someone did a dyno test with 3 different scenarios and I don't remember where I read that....the tests were with stock arrestor, no arrestor, and K&N arrestor.....the bottom line was that there was no difference between having nothing and having the stocker in place....why not stick with the stocker, unless of course you are worried about filtration and then maybe the K&N would be a better solution???? If there are gains to be had with the 496, chances are this isn't where you'll find them.