As I suspected, the odd sound in the corners is an anti-lag system, similar to what the F1 guys were doing with EBD's, but using an off-throttle map to keep the turbo's spooled up instead:
"In effect, Hameedi said, the GT delivers the same throttle response one might expect from a turboed race car with special anti-lag hardware. In grossly simplified terms, these systems dump fuel directly into the turbo to keep them on boost.
“Obviously, you can’t do that on a production car—the [catalytic converters] would get a little upset.” Hameedi said. “But we’re accomplishing that same end goal purely with software operating in the background to keep the turbo spooled. These are complex algorithms that are completely seamless to the driver. All they know is that when they step on the throttle, the turbo and torque is there.”
Like I said, it's a very unique sound you don't normally hear on most race cars, but unmistakable, when you do.
If you're interested in how this works, click the 'these systems' link under "A software response to turbo lag"' and scroll down to "How ALS Works".
There's some pretty interesting tidbits in the rest of the article about the car:
http://www.pcworld.com/article/29172...-know-why.html