I just bought a 05 Mazda tribute inline 4 fwd and I am wanting to put a straight pipe exhaust and a cold air intake on it. I don't know if I have to reprogram the computer because of the back pressure change, I need a little assisstance. I'm planning on removing the cat or replacing it.

 

You CAN remove the cat-converter yourself but if you get caught its a $2500 fine in all 50 States if they press charges. Now that that is out of the way if you remove the cat you will need to trick the computer into thinking it is still there since there is/are O2 sensors after the converter to check that it is still operating. Alot of States even prohibit running your car without any form of muffler so you will have to have one installed but it can be just a glasspack if you want. Where do you live?

And welcome to the forums! If you could fill out your signature (look at mine for example) so when/if your post gets burried we still know which vehicle we are talking about

 

Is there not 2 cats on a 4 cylinder? Pre-cat and main cat? The O2 sensors would be before and after the pre-cat, so removing the rear main cat would not make any difference. Putting a straight pipe after the pre-cat would not require computer reprogramming, however, you should disconnect the negative terminal on the battery (followed by immediate pressing of the brake pedal) while the work is being done. Sfter the work let it idle for 10 minutes before driving. Computer will slightly re-learn after 50-100 miles.

On a V6: I have a 2006 Mazda 6 3.0 litre and my car has 2 pre-cats and 1 main rear cat. O2 sensors are before and after the pre-cat. Some 2005 models had 2 rear main cats. If yours is the single rear main cat, hopefully your crossover Y-pipe doesn't look like this: https://www.mazdaforum.com/forum/maz...-design-28940/ (first picture). If your exhaust looks like that, changing it further back will not help you much, you must change the design for both power and sound. You will get some sound change removing the rear main cat and straight pipe.

Cold air intake does not require reprogramming, just battery disconnect. If you get codes from it, you need an "air straightener" (example: http://www.jscspeed.com/catalog/AEM_...d3-5016-1.html ) or a different model as not all work properly.

Removing Cats are illegal and then you can't sell your vehicle either without replacing them.