If I have three catalytic converters, can I delete the two in the manifolds and just keep the downpipe cat?

REFRIGERATEDTP

MEMBER
2005 TOYOTA CAMRY
3.3L
V6
2WD
AUTOMATIC
210,000 MILES

Hey guys, my stock exhaust from 2005 is Swiss cheese at this point. I need to get a drop-in replacement. MagnaFlow has a nice 3 piece (2 manifolds, 1 downpipe) each with their own cat. Why? I don't live in California, Colorado, or NY, so I was wondering if I could just purchase the downpipe and either google my ass off to find some non-cat manifolds or get some made from a local shop.

I drive this thing hard, and that's what it's for until something drastic to the drivetrain happens. I might even fix that too. If deleting two cats will improve power in even the slightest way- I'm down.

1 Reply

STEVE W.

MECHANIC
13,465 POSTS

The short answer is no. Your vehicle also has 4 - O2 sensors. One in front of each cat to tell the ECU how to run the engine and two after the cats to tell it how well they are working and to act as a second input if the first one were to fail. These are also required under federal law. It's a federal offence under the clean air act to remove them and it will not improve the power in any way because they can flow far more exhaust than the engine puts out. However, removing them means that now the two downstream sensors will set multiple codes as a start. As far as a shop making you the manifolds, most shops are not going to do that because it carries a large fine and possibly being closed down and going to jail for doing it. Plus, as of a few years ago the Federal law applies those same fines and terms to individuals as well as to shops.

https://www.epa.gov/sites/default/files/documents/exhsysrepair.pdf