MPs aren't EPA-approved, so they're technically illegal to run on the road.

 

so they just say that for legal issues... I think i might take a chance..

 

It is always illegal to remove emissions equipment, no matter where you live. Some states don't check though so you can get away with it. Also, interestingly, it is illegal to replace your cat if the one you have works properly. I'm all for at least one cat because you don't sacrifice very much power for a way way way way way cleaner running car. You can pass smog with an airpump and a HF cat, and that will cost about 10HP even in a fairly highly modified car. Your HC's can range from about 20ppm (with properly working emissions equipment) to around 1000ppm with a midpipe, so you're polluting the environment 50 times more for very little benefit. The thing that annoys me is the visual check...

 

Well, That's interesting.. i do see that.. but couple of questions.... please clearify to me as maybe someone else might be interested..

Catalytic converter does two things.. reduction catalyst (where Nitrogen oxides are seperated to N2 and O2) by means of platium, rhodium, or palladium.. and oxidation catalyst where unburn fuel, heat and o2 from precious metal to get rid of excess hydrocarbon.

And the thing is the location of where air pump hooks up on the mid pipe.. I guess I'm missing the point that heat is essential for those metals to work properly to seperate nitrogen oxide and using the o2 from nitrogen oxide to burn the unburn fuel?? and that air pump will supply the air needed to burn off the excess unburn fuel??

Also, I'm not sure about this but Doesn't flow rate on the air pump is pretty high at idle?? I'm not sure what that rate is.. but i remember it was sucking quite a bid of air.. and how much air is needed?? I guess i'm still stuck to the idea that it dilutes the exhaust gas than air pump helping acturally reducing emission..

But i could be completely wrong.. as I do see others points..

 

http://auto.howstuffworks.com/catalytic-converter2.htm

Heat is necessary/aids/speeds up the majority of chemical reactions. The chemical reaction of the oxidation catalyzer is one of them.

Read the last part of the above link, or my previous post.

Well, you're gonna have to ask a Mazda engineer about those questions.

Heh, yeah....well, it's a free country, and you can believe what you want. I'm just trying to give you the right information, instead of letting people come to conclusions based upon heresay, hunches, guesses, or inaccurate info.

 

Kento,

Thanks for that info.. now I think I understand why they put the air pump air piping to the mid of the cat converter..

That link is very useful..
As seen on that link, The cat is divided in to two sections. One the reduction and the other oxidation..

As me and Kento both mentioned.. The reduction stage seperates Nitrogen and Oxygen.. The oxidation portion is where O2 is used to burn unburn hydrocarbon.. now it make sense why O2 pump is hooked up at the mid.. Where O2 is pumped.. post reduction..

Well, It clears things up for me.. And Thanks again for your insight and link..