So they do that from heat. Or strain in them. Because once complete there will be no strain on them.

 

If your taking about the flexes, it's from the hot exhaust pre-tubro blowing though them very fast, expanding the SS mesh and then the force of the gas going through them, sucks the mesh out of them. Every one I've ever cut apart after running a while has looked like that or this...



I went away from flexes in my cross over complete a few years ago just because even the "good" ones only last a couple years before they fatigue, crack and start leaking. I use slip joint with SS stretch clamp to seal them, or weld them solid once installed. No problems since.




If you must use a flex, use this type. I use them on my waste gates since they don't see near the flow as the crossover does and they seem to last a while.

http://www.treadstoneperformance.com...Coupler+Bellow

 

Ive had my flexes do the same thing just after a short 2 day drive. They dont hold up. This is what i done. I pulled the mesh braid out of mine after they blowed apart and rewelded the joint back in. Once u remove the mesh they look just like the better joints with the bellow inside.

 

What motor & manifold is that?

 

4.8. Truck manifolds