Thanks for the info guys! Sorry about the newbie error in posting in the wrong forum. I've started a new thread over on rennlist as it seems the 997 forum is more active over there.
997.1S Exhaust/Mufflers - Rennlist Discussion Forums
I'm considering 200 cell cats as well. While I do want more sound I want to be careful not to turn it into something that's overly aggressive. Did you feel like the 200 cell cats were still good balance between quite under low load/low throttle acceleration and cruising and loader during hard acceleration?