I used a Milwaukee fuel 1/2 Mid torque impact and was able to stretch 3 stainless pipe, it did take a few times and a few rotations to get it to open up enough, I think with a more powerful air impact or the larger fuel impact it would work a lot faster. I have previously tried a harbor freight stretcher and it wouldn't even attempt to stretch the pipe.
Rating: [5 of 5 Stars!]