The pipe connection immediately after my catalytic converter is separating and leaking exhaust which is hopefully the cause of my p0420 code.

I'm tempted to just leave it as is and seal it with muffler sealing putty, then wrap it with Fiber Flex and re-clamp as well as I can, but I thought I'd post here to see if anyone has any suggestions for a better DIY fix. Do they make something I could use to pull the pipes back together?

 

That looks like someones idea of a 'fix' for something or other. I think the pipe on the right is supposed to slip inside the pipe on the left...... But, given they have been muffler-clamped, my guess is that won't work any more. I would be tempted to pull both clamps, have someone stick their foot against the muffler, shove it forward as far as you can, then weld the pipes.......