I've done numerous searches, but can't find any answers. I was wondering how exactly removing the cat in the up-pipe ( by means of installing an aftermarket up-pipe) if the car will still be emissions legal (in CO).

Also, I have the same question for the exhaust system (downpipe, and on) . Would removing either of the two cats cause the car to fail emissions? Is there a system that takes out one of the cats and has a single larger-flow cat?

 

There is a difference between "emissions legal" as in being able to pass the emission test in your state, and just plain "legal". People in your local area will probably tell you what you can get away with, but remember that it is a federal offense to tamper with or remove any emissions equipment, cats or otherwise.
Also some states will do a physical inspection as well as a tailpipe test so even if it is still "clean" enough to pass you may fail if they see you have removed cats. It is highly unlikely though that anyone could tell if there is an uppipe cat in place or not, and the uppipe cat is there mainly for cold-start emissions so it won't cause you to fail if the other two cats are still there.

 

Thanks Mulder!

 

Yeah, just removing the uppipe cat will not cause you to fail the sniffer test. But a work around if they do tight visual inspections in your area is to just gut the uppipe. People who have done this say it is pretty much the same effect as buying a catless uppipe plus you wont fail visual inspection.

 

What those guys said. It is against federal law to tamper with your emissions system, period. Your likelihood of failing a smog check because of a catless up-pipe is quite small.

 

California emmissions laws suck.

 

hehehe i live in NH and they dont do emmissions tests here!

 

You are violating Federal law if you tamper with any component of OEM emissions equipment within the first 7 years, I think. I'm not sure about the 7 years, but I am sure it is federal law. While some of the execution of emissions laws makes no sense, the necessity of them is clear. We all have to breathe.

 

its not 7 years in Cali, its 60,000 miles. but you will definately not pass a visual with cats missing. all it takes is a case of beer and an extra $50 or so and you should be able to pass ; )

the things you have to watch out for, especially in CA is the mobile smog checks done by the Highway patrol...they say they randomly pull people over that are driving through the check point, but of course they will pull you over if you come rollin through with a loud *** boxer motor poundin away.

 

It has been speculated that most mechanics doing the visual inspection of a smog check won't be that familiar with a WRX engine and therefore would probably not notice that the "pre-cat" is missing in the up pipe. It is kind of buried in the engine compartment by the intercooler and turbo heat shield, plus it is a somewhat funky layout (H4). Worst case scenario is the case of beer method.