[speeder]

Any really strong impact wrench should do it. You would need to torque it to 250, or however tight you can accurately get it with your wrench, mark the bolt with paint and then blast it with an impact that moves it a hair. Just a hair, at those torques. Threads only stretch so much.

The suggestions about having strippers or 4 German Shepards standing on a pipe assume that there is no friction to overcome in initially moving the fastener. That is an incorrect assumption.