I'd like a certain someone to explain why a spray paint gun works if air and liquids do not behave the same. And how the venture effect discovered by Bernoulli https://en.wikipedia.org/wiki/Bernoulli%27s_principle does not apply to a an exhaust manifold with a crack in it.
BTW this is the same effect that allows planes to fly. The speed of the air going over the wing is faster than the air under the wing creating a low pressure area above the wing. Nature abhors a vacuum so the wing is "pulled upwards" to fill that low pressure area.
Amazing what you learn when your curious.

 

I have found that most headers will eventually crack in an XJ.

The only thing that stopped it for me was welding a flex tube in the down pipe. A exhaust shop can do this pretty easily on the cheap.

Also I have found that header wrap will rust the pipes faster. If worried about heat damaging the rubber in the motor mount, wrap the mount with that aluminum looking heat guard stuff with wire.

 

Yeah, I am spending a lot of money to learn stuff like this.

 

Great info BTW.
I'm replacing the 3rd set in as many years and was looking at the flex as well.
In your experience, how much time have you accumulated with the flex joint now?

 

About three months in my personal jeep.

2 full BITD Jeepspeed seasons with the racer.

Seeing how good it worked on our jeepspeed, I decided to do the same to mine after replacing my headers.