I won't be back at my computer for a few days...but with that pulley and no restrictive plate that car has to be in the 800rwhp mark then. I think the rear in tank pump is good for around 800rwhp on gas so on e55 I can see it running out of fuel. I think with the in tank pump resolved and since you have a lash caped lt4 fuel system it may do 800rwhp on e55 at 20mpa, just have to see where your at.
From what I know the zo6 and stingray have the same rear pump and I've seen another tuner push 72x or so rwhp out of a stock z06 fuel system on e5x!!!