There are several of the diesel trucks in the tens. Twin turbos are not uncommon, nor is propane injection. I know of more than a couple of the Duramax powered trucks that are making right at 1000 foot pounds of torque at the fly wheel.
Here's a short video of a Duramax running 11's. Click on the link to the video that suits your connection.
Fast Duramax A programmer, a new airbox, and some exhaust work will put most Duramax trucks in the 13's without too much trouble, and wuithout hurting the trucks utility as a truck. I sell the Bully Dog stuff, with K&N air boxes and Flowmaster exhaust, the stuff goes on just about every tow vehicle my customers buy. All report dramatic mileage increases, and driveability improvement as well.
Regarding the 3800 Series II V6, it's a great engine, I own one myself, in a Firebird, and I love it. i've seen the give the best service of any V6 on the market.
As to questions about 700HP on pump gas from a small block, well, it's pretty easy to build a 427 small block with off the shelf parts. With the current crop of killer heads on the market, 1.65HP per cubic inch with 10.7: compression is not a problem. And yes, with the right cam and proper tuning, you can run 10.7 on pump gas. Granted, it'll have a solid roller in it so you'll have to run the valves every so often, but that's no big deal.