Muffler Advice

500 cfm per muffler..does that even relate to exhaust? Seems it would flow lots more than what it takes in...? We are not talking a pump here.

We are talking about a pump of sorts only it pukes out
hot expanding gasses that need to stay moving in a smooth
orderly fashion with a minimum of restrictions so it can scavage correctly with some means of sound attenuation.

Why would I spend tons of money on an engine(like I have)to make
everything flow its level best, then not do the same for an exhaust system.

If I'm using a set of 2 1/2" pipes capable of 1000 cfm and choke them with a set of mufflers rated at 325 cfm each or a total of 650cfm it kind of defeats the purpose in my mind.

I am asking for mufflers that flow at or around 500 cfm each and
still control sound at a reasonable db level so I'm not a target for
every Barney Fife in the county, if that's possible.

I'm not sold on any muffler yet, I'm still planning the system
and looking for advice.