Looks like an aftermarket install. It looks exactly like an LSA out of a CTS-V as in a crate engine. It could be a GM Powertrain test car, like the LS7 powerd 4th gen they had.
None of this looks like an engineered set up. It looks like it was just put in, hooked up some fuel, home built intake, and on the road she went.

 

Im just pointing out that this is EXACTLY the kind of language magazines used in 06 when they used renderings of what the concept 5th gen MIGHT look like IF GM decides to build one. It was intentional to get you to buy the magazine.


Having said that, this could be a mule for the Z28 drive train, and I dont know this writers style, or it could be a car they built and suggested the Z28 MIGHT be similar so that you'd buy the magazine. Certainly wouldnt be the first time a car mag pulled this. Not by a long shot...

 

I don't know if there were pics' that were posted that I can't see, but if that's the engine CC says is going in Z28, that's an LS9; I can see the Wixom assembler plate on the side of the upper intercooler housing. Sorry if I'm missing something

 

I think the motor is this one not a LS9.