The Thursday night meets are a great event, most people aren't even past stage II so I don't know what that chatter is about. There's lots of knowledge there and more often than not some of the great tuning minds in the subaru scene. You'll get to see everything from mild to wild cars. . . about the only thing that's not welcomed is stupidity and rice.
Honestly, if you're modding plan for the fact you're going to get an exhaust ticket.
Emissions via OBDII is just a scan, if you have a fix that doesn't just cover up the CEL you'll pass.