How to expand 3" exhaust pipe to create a slip fit joint

How does one expand the end of 3" pipe in order to create a slip fit joint. I have tried the expander that tightens up with an impact wrench, did not work on 3" pipe.http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=37354

Do muffler shops have a bigger machine than can do this? Anyone have another way of doing this?

An exhaust shop can do it. Might be your only choice if the expander didn't work.

Bring it to an exhaust shop, they'll probably only charge you something stupid like $3. Most wont even charge you, in hopes that you just give them a tip, for something like this.