Was shopping for a new OEM muffler

And found 2 different part numbers:
MN153192 - for cars made between 12/2002 - 07/2005
1571A237 - for cars made between 08/2005 - 11/2006

Apparently second one is Evo 9 muffler and a bit more expensive

Is there any difference in flow/sound?

Will the Evo 9 muffler fit on my stock Evo 8?

 

The evo 8 had a valve in the muffler evo 9 does not.

 

Do you know which one is quieter when idling?

 

I don't know, my suspicion would be that the evo 8 would be quieter at idle due to the flapper valve being closed and only opening under high flow / pressure.