agreed on most of those points. gm stopped using the 5.7L 350 back in 2000 and was a single valve design (1 intake 1 exhaust), older technology and a completely differant motor design. takes almost nothing to wake the 350 up.
with the diesel upgrades look at what audi has done in the thread i started "even meets commifornia emissions". small diesel engine thats incredibly clean and powerfull, the fuel economy estimate was done on the autoban so forget 70mph fuel economy testing, would be higher than what was stated.