Roger,
Unfortunately, the 'pipe-bender' type tools can't do a good job on tubing. The non-mandrel bent elbows in the typical stock exhaust system are what you'll get with tubing vs. pipe in this type bender. My car's headers were made with a pipe bender instead of a proper mandrel bender and they look pretty crappy. Here's some info on the subject and a semi-inexpensive ["only" $500] option:
http://www.lowbucktools.com/hydbender.html
Dan