I used to work as Night Foreman for a big paving company
that had over 300 trucks. We used those type of clamps
routinely to assemble exhaust systems.
I recently found out they also make them smaller for
car use, and found them at a local auto parts place
for around $10. (Summit sells them but gets quite
a bit more, plus their handling fee.)
They're the clear deal - they allow you to assemble
2 pieces of pipe end to end, without slipping them
together or having to have one end smaller or
larger than the other. Also, then you can take
them apart very easily, just remove the clamp.
No expanding the pipe or fighting to get them
apart.
Those clamps are reusable many times, are very
durable as they're stainless, and even allow for
small mismatches in angularity and small gaps
between the ends.
http://www.lincolnsonline.com/article91.html