I have a Brenspeed tune, also. Did you get tunes for different octane fuels? If so, you'll notice the biggest difference with the higher octane fuel and tune. I got mine as a package with a CAI so maybe a tune without the CAI is not much different than stock?
I went, too! Not as many cars as I've seen there in the past! I don't think it was promoted like they used to. Damn, I missed that 2013 GT500! I saw it but didn't even realize it was a 2013! Lots of nice cars and great weather.