Just as a reminder, SXSW starts this Saturday so it would be a good idea to get as far away from downtown Austin as possible lol..
There is the Saturday Cabela's meet that Budwise mentioned. If I'm not too busy I would probably head to that, definitely willing to meet up earlier if I can but...
That's exactly it and in my opinion, I bet all they did was upgrade the intercooler to get to 320HP. Obviously no one will know until they get their hands on it but I think a big tell is how huge that front portion is. Just look at the thing...
I wrote up a pretty lengthy review with some pics on the Cobb AP
http://www.mustang6g.com/forums/showthread.php?t=13123
You could always check that out if you're interested in learning more from my experience. Obviously I'd say go with Cobb hehe.