Awesome Dave!! I remember how nervous and strange I felt when my engineer was driving my 240z and stomping on the brakes during the test. No one before or since has driven it besides me.
Get used to lots of staring, pointing and thumbs up, people taking pics at lights, and being bailed up to chat cars every now and then. Without sounding narcissistic, its satisfying for all the blood, sweat and tears that go into these builds.
Re the exhaust: you could always get a silencer for the tip just to help get you through the engineers as a temporary solution. I Dynamated my rear end and it did make a big difference for cabin noise..