I hope MSD finally got it right this time. A few years back if I can remember they had one for the 5th gen LS3 and it was pretty disappointing as far as performance results.
http://www.camaro5.com/forums/showthread.php?t=383527
I believe they wound up pulling it from the market because they couldn't justify that it made any more power over the stock manifold.
Good luck guys. If it gives you another 10-15 rwhp over stock, I'm not sure I'd pay 1000 bucks for that. If it's closer to the 50 that they advertise then maybe.