There are a few contenders for the most powerful 3/4 impact wrench title. The Ingersoll Rand W7150-K22 is one option that produces 1,350 ft.-lbs. of torque at 900 RPM. Another is the Milwaukee 2763-22 M18 which delivers up to 1,700 ft.-lbs. of torque. For something a little different, take a look at the Dewalt DCF899P2 which maxes out at 1,825 ft.-lbs. and also has a brushless motor for longer runtime between charges.