There are three ways to bend pipe. The first is to use a "ram bender" where pipe/tubing is bent by a jack… More
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Summary: Expand a tail pipe to compensate for muffler-cramp impact by increasing its diameter with a pipe bender using the tips found in this free auto-repair video.
Doug Jenkins runs Doug Jenkins Custom Hot Rods in St. Louis, where he restores classic cars and creates mild to wild custom street rods. He races a 1972 Corvette in the SCCA...read more
"Hi, I'm Doug. I work with twenty great guys in St. Louis at Doug Jenkins Custom Hot Rods and we're going to do some work for you today on Expert Village. Now, Dave is going to use a feature of the pipe bender that allows him to expand the end of a piece of pipe. We're using this older pipe here that had been on a car before, and he's expanding the inside diameter of the tail pipe to compensate for the way the original muffler clamps crushed the pipe a little bit. This is just to aid in the test fitting there because the pipe has to come on and off of the muffler a few times in order to get everything lined up perfectly. We determine where to put the muffler based on where the tail pipes look best coming out. Since we're using pre-bent pipes on this job there's a little bit of an adjustment we have to do to make things look real good. So, here he's expanding the pipe again just to get it as big as he can without having it so large it won't clamp back onto the muffler. And he'll test fit this a few times."
eHow Article: How to Expand a Tail Pipe