I know of a few turboed modular GTs...
A couple things....
Overall, the turbo kits will run a little more in parts cost compared to the blowers with around the same gains...
and if you're not putting it in yourself, the turbos will run more cost in installation...
The stage I TDC kit costs a bit more than my Procharger unit with less power output....
The stage II puts out some good #s but costs much more than comparable blower kits (parts cost)...
One last thing...
the high powered TDC kits may be good for 600 horse, but don't expect to strap a turbo kit on a stock engine (or any other kit for that matter) and expect to see that kind of performance improvement.
The stock engine internals just weren't made to handle it, or the stock fuel system, nor is the stock transmission, or the frame....
You just can't keep dialing up the boost until the desired rwhp number comes up on the dyno...
Don't get me wrong, I have absolutely nothing against turbo setups, but it seems that the turbo is this year's "thing" and everyone seems to be caught up in the hype.
In my opinion, if you're serious about a reliable 500 rwhp GT, start with the engine...
298 ci stroker kit with forged internals
ported\polished heads and after-market intake (preferably Ford Motorsport)
upgraded fuel system (maybe an aeromotive pump and some big injectors)
upgraded ignition (maybe an MSD unit)
full performance exhaust swap
a forced induction unit with a "sane" amount of boost (blower, turbo, or nitrous)
custom programmed and "tuned" chip
the above combo should net at least 500rwhp with a nice powerband. Remember that the higher you pump up the boost, the harder it becomes to tune the car for reliability....
Run the above like a banshee until the tranny\rear end dies and get yourself a world class T5 and 9 inch rear...
I'm not even going to get into the frame and suspension mods to get that power to the ground...
Just be safe out there and have a good time...