Well I found it is actually an article at Popular Hot Rodding's site. It's just them daydreaming about it though, the writers refer to it as "their" GNX, just a design they made up based on the GTO platform.
And the turbo? Forget about it. A major redesign of an available V-6 or V-8 engine (needed for a turbo) would cost too much and drive the price right into the stratosphere.
http://popularhotrodding.com/features/0510phr_spread/