How many cats wrx

Not to worry you but if the cat in the up-pipe fails Fair one! If you get a replacement cat pipe with a hole for the o2 sensor you won't get a CEL The downpipe cat must get mapped if you remove it You will only get a CEL if you start removing the o2 sensors or the temperature sensor in the up-pipe.

The temp sensor can be removed and you can put a resistor in the plug to remove the CEL. You can post now and register later.

If you have an account, sign in now to post with your account. Paste as plain text instead. Only 75 emoji are allowed. Display as a link instead. Clear editor. Upload or insert images from URL. How many cats do I need to lose until i'm deemed a hooligan? Share More sharing options Followers 0. Reply to this topic Start new topic. Recommended Posts. Danpow Posted April 21, Posted April 21, If the code returns which I doubt then think about catalysts. If it turns out that you do need new cats, those prices look about right.

The only way to save money there is to pay a muffler shop to weld in generic cats, which might be fine, but I hesitate to suggest it. PPS - the first line of my post said four oxygen sensors. My mistake. The muffler was going bad tho. The Subaru Impreza Exhaust explained. Inside a catalytic converter are metals like platinum, Palladium and Rhodium. Although these precious metals are a catalyst they do eventully become used up although very slowly. A normal catalytic converter should last the life of the car but other factors can cause them to fail premeaturely.

Decat - To map or not to map Removing some or all of the catalytic converters by replacing them with straight through decat pipes enables the exhaust gases to flow more freely through the exhaust which means the turbo can be moved faster by the faster flowing exhaust gases. The risk that this poses is that as explained in the turbo section a faster moving turbo will force more air into the engine causing the balance of air and petrol mix flowing into the engine to be upset.

Although the engine management system will try to compensate by using the sensors on the car to calculate the changes it is quite possible that the increased airflow will cause this mixture to be lean too much air and not enough fuel.

This can cause the engine to run hotter than intended and can result in engine failure. Therefore if you are intending to remove some or all of the cats and uprating your air filter to a higher flowing air filter it is recommended that you have the engine management system reconfigured ECU remap to take account of the increased air flow.

Changing the exhaust alone will increase the bhp but the most gains will be made by having it properly remapped.

If, for example you gain 15bhp by changing the exhaust and air filter then you may be able to gain 40bhp if you had it remapped as well bhp figures are an example only.

Also new legislation regarding fitting catalytic converters to cars registered after 1st March Cats fitted to these vehicles must be "type approved for the vehicle" for road use, therefore all aftermarket non "type approved" cats fitted to vehicles registered after this date must be considered for off road use only.