Foam or Polyfill in a 4x12 cab ?

[ApolloSpeed]

Just curious.....would some sorta foam or polyfill do good for the sound of a 4x12 guitar cab ?

I was just wonder how that would make sound on v30's in my cab recorded ?

anyone try this ?

I know Gens-Benz has ported cabs, but I never heard a good Gens-Benz sound yet!