My catalitic converter sounds like it is full of rocks. I had my check engine light flash for a minuite the other day and it whent away. The only way I would how to check the cat is with a sawazal. I'm 99% percent sure that's what it is. Is there a better way to check. And if. Decide to straight pipe it will my check engine light always be on. My OCD won't let me drive with any warning lights, rattles, squeeks, bangs, or whines so check engine= don't drive

 

Thump on the cat with a rubber mallet. if you here the box of rocks thing, yep. It's toast. Gut it.

For the CEL, it may or may not come on. If it wants to come on regularly, you can just grab a couple spark plug non-foulers, and modify them to keep the post-cat sensor from being annoyed. There should be a DIY in the FAQ section on that.