If you look at the link, you'll see how much he had to cut out. He also built custom sidebars that acted as induction pipes. Even though the guy did seem to do quite a bit of fabrication to restrengthen the rear end of the car, I question the integrity of the unibody after it's had that much cut away from it. I think the turbo setup is questionable, because the turbos are mounted so far away from the engine, there is going to be a great deal of heat loss which will hurt the efficiency of the turbochargers. I know there is a company that makes a turbo kit that mounts under the car near the muffler, and the work pretty well on the F-body cars, but still, I don't think it's an ideal setup. That, and any water splashing up from under the car is liable to shock cool the turbochargers. The whole point of the setup is to try and hide the power adders. But with turbochargers that size, there is no way you're going to drive that car, and not have someone hear them spooling up. So I think it was a pointless effort to do all that fabrication.
Kurt