Need some help on an emissions issue, Cat relocation: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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March 27, 2011 11:35 p.m. neckromacr Reader

I'll cut to the chase: I have a car that originally had a manifold/downpipe/cat set up that now has a cat-less header welded straight to the midpipe. I need to get it past tailpipe emissions, and without a cat obviously it's failsville.

I'd like to keep the header since it's in good shape and flows a little better.

I was thinking of taking the mid pipe resonator out and welding in a universal cat. In the OEM setup the only O2 is pre-cat and technically it'll have all the proper emissions components, just not in OEM configuration.

I figure I'd tap the GRM community's wealth of knowledge and see if this was a terrible idea.
March 28, 2011 12:43 a.m. Nitroracer SuperDork

Might depend on how closely your state follows the inspection rules. Some places will not allow the position of the cats to be changed.

I would call a local exhaust shop and run the idea by them.
March 28, 2011 8:30 a.m. davidjs Reader

I'm not sure how far back you are looking at putting it, but you may have issues getting it hot enough, so I would probably make sure you ran it hot for quite some time before getting it sniffed, just in case?
March 28, 2011 9:16 a.m. iceracer Dork

Each state has different regulations, best to check locally.
March 28, 2011 10:56 a.m. mad_machine SuperDork

yes.. I would think that getting it as close to the header as possible would be best
March 28, 2011 11:22 a.m. Travis_K Dork

Check the local regulations, in california you would be putting it back to stock, but other places dont care at all, it just depends.
March 28, 2011 3:44 p.m. neckromacr Reader

Talked to a friend in the DMV, Delaware only cares that its in the exhaust system somewhere.

But the location in relation to the header is why I asked here, thanks.

For comparison's sake TT's exhaust mimic's the OEM one pretty well. The midpipe resonator would become the cat.