[quote author=GhostCruiser link=board=2;threadid=5209;start=msg40644#msg40644 date=1063399773]
What reasons would a guy have to keep a cat on with no state registration inspection?
The main reason would be because it is illegal to tamper with or render inoperative emission control devices on vehicles registered to operate on public roads.
That being said I don't know what the exhaust cops would do to you if they decided to ticket you. IF you do remove anything I sugest that you keep it in case you are required to return it to it's original configuration at some point in the future.
A foot note: I would look VERY hard at a purchase of a vehicle that did not have all of it's emissions components either present or in a box in the back . Any subsequent requirment to put the stuff back on to register the vehicle could break the bank if new parts had to be purchased. If you had such a vehicle and wanted to get rid of it, it would be vurtually sale proof.
Modern cats are pretty free flowing. You may see a minor performance gain in a 3FE if they were absent. It has also been noted earlier in the thread that the O2 sensors are ahead of the cats so that would not be an issue. I think that in order for you to have a meanful impact on flow you need to address both intake and exhaust sides of the engine. BTW a lot of our Emission related laws are federal, not state. You certainly can do whatever you like, the only reason I mentioned any of the legal bits is to be sure you make an informed decision about any changes you may make. I wanted you to be aware of some of the potential issues you might face in the future. Montana is not Los Angeles or metro Phoenix or Salt Lake County yet.
In Aus, none of our models had cats, but what we do.. oops I mean what can be done, is get the exhaust shop to seperate the cat, and remove the inside, then put the case back around the pipe which now runs full length, so the exhaust look slike it has a cat, but unless you took the exhaust off, you would never know.
All the cat does is burn off the sulphur, which is the smog component you can see, [the haze around the city] they were fitted as a cheap option compared to oil companies cleaing up the fuel they sell.
Diseasels make up 80% of all visible pollution in out towns here though.
My 60 had a leaking cat. Removed it and it had the old style cat, you cant see through it. I didn't like the smell of the exhaust and got the Downey 'free flow' cat under $100. You can see through it.
If you have the see through cat, your screw driver might slip and brake something.
If you have the one that you can't see through, ditch it and make a 'test tub' (they use to sell them to test the cat but no one ever put the cat back on).
If you ever want to have a muffler shop install new exhaust, you WILL need a cat there or they WILL be fined. I think the downey cat was $68 or so.
So, if I remove the cat, I should no get any check engine light on my 92 FJ80? I want to remove it because all is doing is waiting to be smashed by a rock. Here in Puerto Rico removing the cat is not a big issue, specially in 18 year + vehicles.