Nice car! GTO is a pain to get in and out of the back, but I had a couple passengers comment that they thought the back seats were more comfortable than the front. I kind of wish I'd gotten a CTS-V instead, it would have been easier to justify keeping a 4 door car. Then I remember the MPG's it (didn't) get and the other costs associated with a performance car.
On-ramps sure were fun.
How's the belly? I'm with you on not doing any obvious mods, but an air dam and/or belly pan would be discrete.