gEEz
Don't even think about doing TT unless you are willing to spend a lot of money and go really fast. Go really fast means pretty wild buildup, custom calibration/computer of some type.
Doing 2 stock turbos is goofy. No reason to.. you'll spend $2000 or so on headers... which he hasn't made to fit stock type heads, then custom downpipes, then custom intercooler, then custom exhaust, then make sure no interference with the propshaft, or steering shaft, remove your ABS, relocate your brake lines in that area, remove your AC, upgrade your cooling system if your IC system dictates that, custom intake/plenum possibly, if you need to accomodate the intercooler pipe. 2 stock turbos will make 600-700hp. I've been in trucks that have a single turbo that supports that HP, and response was great IMO. It was traction limited at that point already...
ATR and KB headers have gone into the 10s on AWD trucks, and could go deep 10s IMO. They've done 9's on RWD trucks already. If you want better response, optimize your exhaust system, get a good stall, and do a ball bearing turbo for a mild truck. If you are doing max effort, or have DEEP pockets and want something different... do the TT setup...
Just my $0.02