My flex pipe is starting to leak also - It didnt help that when I was trying to remove the aft O2 sensor the flex joint took a beating. I ended up having to remove the mid pipe so i could break it free. I would like to replace the whole exhaust manifold with a straight pipe / high flow Cat. Couldn’t find anything either.
you may need to go an exhaust fab shop or find a buddy who’s good at Tig Welding Fab something up.