I am looking into replacing my y-pipe on my Se. I was thinking about optimizing it but my flex pipe is looking pretty ruff and its stock with 77K on it. I have a 2.5 brullen cat back and I am considering the BAT y-pipe with hiflow cat.
However I notice on my y-pipe (ATX if that matters)the flex is before the cat and on BAT's its after the cat. Is that going to be a problem? Would it be better to find a y with the flexs before the cat, if they even make it?

The flex piece is a separate unit flanged to the rear of the stock Y-pipe.

Optimize the stock Y-pipe. (remove crush bend and add 2.5" outlet flange)


Then build your own intermediate pipe between it and your cat back. This is also the section you would mount the main catalytic converter in.