Many don't that you need to carefully slot the cat for using clamps. Unlike many "adapter" at parts stores... Cat metal to hard etc for clamps.
Covered in many books and GM SM.
I look later.
I use slots and 2 clamps.
Clamps are 180° to each other and close together as possible.
They make exhaust "sealer" too to use w/ clamps to stop minor leaks.
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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)