I've got a custom 2 ½” exhaust on my 13b with a Bonez cat.

I couldn't pass emissions last time I tested so I just had the cat replaced with another Bonez (had to be welded in). When I asked to see the old one, it was absolutely cleaned out. There was no sign of the catalyst. It was only about 2 ½ years old but it had a pretty hard life, still, I'm a little disappointed.

Knowing this, I'm impressed that I actually almost passed the e-test with no cat at all. It must have disintegrated slowly because I never noticed how much louder the exhaust was getting but it is noticeably more quiet now.

The bummer is that I probably should replace my muffler now to get out all the cat pieces.