What are the benefits of taking out your catalytic converter?

I'm starting to learn about exhaust systems in cars. My friend just bought a new subaru legacy 2.5gt. He said he wants to make his exhaust full catless. From what I know, you need your catalytic conv. to reduce emissions. If you don't have it in, isn't it illegal? won't you not pass emissions testing?? Also, what are the benefits of taking out the catalytic converter? (since it seems to be a common mod)What are the benefits of taking out your catalytic converter?
None. Today's engines are designed to work with a good working catalytic converter.



JD
Taking out the cat will improve fuel economy and power. HOWEVER, it is very illegal. You will NOT pass emissions, etc.What are the benefits of taking out your catalytic converter?
removing the cat is illegal. also the warranty will be void. it can not pass emissions.
Small power increase.



However without a cat you will not pass emissions, and will receive a hefty fine if you are caught without it. Today's cars are built to run with a cat, don't remove it.What are the benefits of taking out your catalytic converter?
the only benefit to removing the catalytic converter is when it is plugged up. otherwise there is no benefit. in fact if you remove the coverters you are breaking federal law, and if you are caught there is a rather large fine you will have to pay. remember that just because the state you live in doesnt require an emissions test, doesnt mean you can eliminate the emissions system on cars that are so equiped.
that cat has a before and after o2 sensor that helps your motor to map.if the numbers are wrong, the engine will not run right.it is possible to pass smog with a modified exhaust, but you wopnt be able to drive the damn thing cause itll run so weak
Removing the converter is the worst thing to do. It will cause the engine to fail before it's time and just stink up the world. THere is NO good reason to destroy what it took a decade or so for engineers to figure out. Converters do NOT rob you of power. Your friend is a total idiot if he does such a thing. The engine relies on signals from the O2 sensors before and after the converter to alter fuel quntity and timing. Tell your friend he is STUPID, STUPID, STUPIID for attempting such a thing. He will ruin the value of the car, and gain ABSOLUTELY NOTHING!! These engines have fuel management precision that produce every bit of power when called upon by the foot pedal under full load. THe fuel is enriched, and the best power is obtained. NO ONE drives their car with the pedal to the floor constantly!!! Your friend will just trash it out and lose power and performance. What a WASTE!!! Try installing a set of Denso Iridium plugs first. Then be SURE that you are using a "top tier" fuel. You will have more power than you need!!
Your friend might find a small increase in HP, however if caught, your friend might find his licence plates seized and a big fine (or a summons, meaning court time etc.) - before he'd be allowed to drive his car again he'd have to pay to have it re-installed. He'd still have to pay the towing fees also after his plates were seized.



The officer might not seize the plates, but that's up to the officer. They seize the plates 'to stop the offence from continuing' - so the cost involved in towing etc. doesn't even factor into the fine you pay. Not to mention if there's anything else your friend has in his car that he wouldn't want a lot of police attention to, it's a dumb idea.



It will fail the emissions test because the visual inspection will fail it even before they put it on the dyno.



Modern cars have better cats than before, you really gain almost nothing by removing them and the risk isn't worth it. Any emissions equipment installed on the car when it was made, has to remain on it (or a working equivalent) and working. Otherwise you pay a big price and get a big embarrassment if you're driving with your girlfriend when they seize your plates and you have to be towed.

sea ray