Just wanted to say I did this mod and am completely happy with it! No more burned oil smell after WOT.
A much improved PCV system now also with no PCV valve!
With LS1 you do have to remove some material on the side of the head that serves no purpose anyway, in order for the improved cover to fit. I used a Dremel cut off wheel.
With my LS1, I didn't need the kit plug but here's the kit I bought: http://www.improvedracing.com/engine...kit-p-633.html
Also changed the power steering pulley from the crappy plastic one, to the updated metal pulley.