How did I miss this thread??? Must have been on Thankgiving weekend!
It's true that Kelly's Falcon is mainly a drag car. However we've driven it all over the place and it does very well on the street. Doesn't overheat, idles like a stocker etc. The only difference is that we have to manually shift the automatic, and we can beat damn near anything that pulls up next to us!!!
We've run her car up to 16lbs. of boost. (by accident

) and I've never felt that the car was going to grenade. It's all in the tune up! If you run the thing lean or if it goes lean by itself due to some failure of a part then yes, you'll probably hole a piston. That can be done at 6lbs. of boost.
I bet Kelly's stock US 250 motor will easily hold up to 20+ lbs. of boost. As the learning curve progresses, her crew chief (me) will slowly start to crank up the wastegate!
Will