I'm sure it's already been posted somewhere, but it occured to me that the orientation of the humps on the upper plenum suggest, to me, that those might be for the intercooler bricks, much like LS9 has in ZR1; which leads me to believe the 2300 might be stuck on LSA in Z28.
Hmm... I'm definately thinking 580+ horse' now
Below is an common image of the upper plenum with intercooler bricks on LS9: