Catalytic Converter question!

[destinharper]

Hey guys, so on my FR-S I currently am running the TRD catback exhaust and I saw it has a catalytic converter on it. I am looking into the nameless performance Overpipe/downpipe combo and wanted to know if I needed to get the catted version of it or not.

Sorry if this is a stupid question, new to the game.
Any help would be much appreciated!

[SigmaHyperion]

I think you are mistaking the resonator (a thicker area on the long straight length of pipe) on the TRD exhaust for the Cat. It's a cat back, meaning it replaces everything from the catalytic converter (not inclusive of) all the way back to the bumper.

Your car has 2 Cats -- one one the header, one on the front pipe. Whether or not you want to go with a cat on your overpipe/downpipe (downpipe == frontpipe) combo, depends on just how compliant to emissions regulations you want to be and how stringent your area is on checking emissions equipment.

Technically, replacing your secondary cat is illegal as it alters your vehicles emissions systems. For most installations, not having a secondary cat won't cause a CEL, which would be an immediate inspection failure, and you'll pass inspection just fine. If, however, you live in an area that does visual inspections on exhaust systems (fairly rare), then it doesn't matter whether you throw a CEL or not, they'll look under the car and see you replaced your factory secondary cat, and you'll fail.

If in doubt, it's probably better to just stick with a catted pipe.

[pcporo]

I live in an area that does not do emissions and have the TRD catback exhaust. I also agree that you are probably looking at the resonator. On the front pipe there is a cat and muffler tho. I replaced it with an invidia front pipe, no cat, no muffler. Love the sound I got and don't get any CEL problems. But I did keep the stock piece incase I do move back to civilization lol.

[destinharper]

Thanks guys, must be the resonator I see. I live in Colorado, not too strict on emissions here. I think I could get away with running the single cat on the header. I plan on doing a nameless performance header when it is released as well and I believe that it will be catted.

Thanks for clearing up some of my confusion!

[wparsons]

If you're going to run a header, get a catted front pipe. You'll want the extra cat to help keep the rasp down with a header.

The header will make the exhaust significantly louder and raspier than stock.