None that have blown out on my stuff have been the mesh inside. Just the flexible pipe kind that just can't take the heat and crack. Easier just to not use them..

 

I used 2.5" 14 ga mild steel from mandrel-bends.com (pretty sure). I bought an extra turbo style flex joint I don't need, highest quality Vibrant brand.
There are three types, no liner (weakest), braided liner (can disintegrate), and turbo flex liner which is the strongest but stiffest.
PM me if you want it cheap.