I would love that much horsepower, just not that fuel consumption!
(Wondering out loud...) I wonder what could be done with a small pair of turbos, a dual map ECU running 16 smaller injectors, and an LSX? Could you make that kind of power and still get 15-16 mpg in normal city driving with better driveability? Also, could you top 30mpg highway with the A/C on and 600 hp in a 3500 lb G body? Theoretically speaking, the small turbos would spool fast and the lighter LSX aluminum block would offset the weight of the turbos. Also, running 16 injectors would allow you to run on 8 of them most of the time, and take advantage of the better metering of lower amounts of fuel you get with small injectors, while the other 8 would provide the fuel you need when you step on it. The dual map ECU would let you run low boost or no boost in an every day situation, but still give you the added power when you wanted it.