I found one - it's actually right near my house too - they have a mandrel bender in their shop. http://www.muffler-tech.com (I have no association with this shop other than I'm considering having them do my exhaust because they do mandrel bending).

 

Just a question for you guys.

What is the difference between say 2 1/4" mandrel bent pipe (so no restrictions in flow at the bends) and 2 1/2" pressure bent pipe?

Assuming the pressure bends in 2 1/2" cause it to lose a little diameter obviously, wouldn't it have the same capacity as 2 1/4" as far as flow roughly? Or would the overall volume of 2 1/2" still be larger than 2 1/4" and thus the exhaust would cool down too much, where as the 2 1/4" mandrel bent flows when you need it to, but it doesn't have as much overall volume?
Do you hear what I'm asking? I hope it makes sense?