Exhaust questions for my truck

I don't know much about exhaust but this is what I'm trying to do.

My whole system is shot, I need to replace the manifolds all the way to the tail pipes.

My system stok is set up with the manifolds into a y-pipe into the catalytic converter an then into the cat-back system.

I'm looking to eliminate the y-pipe. I have a page that has pipes labeled extension pipes and intermediate pipes. Would one of those go from the manifolds down into their own cats?

Or would I have to look up a x or h pipe? Or is i not worth it. Should I just get the performance y-pipe into a single cat and then the cat-back from that?

I have a 1989 Chevrolet 2500K 3/4 ton pickup. Regular cab long bed. 5.7L 350 V8 just for reference.