Mazda Talk Forums

Currently living in Illinois where we have periodic emissions tests. I would like to install the header and midpipe that gets me the most HP/torque and still can pass the emissions test. Is that a possibility? What would I need to buy to get the job done?
Thanks
Tom

next to impossible.

Remove header and mid pipe means remove two cat converter. No way you can pass any emission test.

He didn't say anything about removing both converters. Not only possible to replace both header and midpipe and still pass emissions, but done all over this country for more than a decade (the 99 Miata was also sold often as a 2 converter car in many states and folks have installed a performance header and performance midpipe with converter and still passed their local emissions tests repeatedly with both the two converter 99 and the 2006 and newer).

In many places the emissions check either does not exist or involves only minimal tailpipe tests that an MX5 can pass with just one converter (our 2.5 inch midpipe still has a converter). Even here in California there are areas that are emissions exempt. I had a home address in Valley Center, California, and my 99 Miata was registered there and it was smog exempt for many years.

Tom, don't know what the rules are in your part of Illinois .....you would want to talk with local club members about that.

I bet it will pass, I live in VA and when I had the header midpipe Q it passed emissions with flying colors. Emissions is just tax revenue and they have crazy high limits on what the car can do. As long as you don't have a CEL the car should pass. Just heat shield the header up with a cover and they won't even be able to see you have a header on the car. I have the turbocharger on my car right now it still has no CEL when tuned right, will most likely pass again since the turbo does not affect the normal cruising because thats what it measures closed loop. Open loop you can dump as much as you want I believe and the car will not even notice it since the computer is not bothering to read the O2 sensors.

jasonMX5 wrote:Emissions is just tax revenue...

You, sir, are incorrect. That's as far as I'm going with the political aspect. I will say you have to check into the laws regarding vehicle emissions inspection in your area, especially how they relate to OBD standards. Where I live, anything younger than 25 years and OBDI requires a sniff test on a roller station. OBDII merely requires reading the ECU for any codes. There is a visual component but most stations don't seem to spend much time on it and it's not nearly as restrictive as Kalifornia's laws.

I'm absolutly correct, I've worked with many people over the past few years and compared the limits allowed for emissions gasses to what cars actually put out. I'm not comparing cars that don't run cat converters to new cars. The cats sure do save the environment. But standards for emissions are low period which equals easy income. I'm also not saying the tests are not requried sure they are. But for a car nowdays without a CEL on its pure revenue 100 times out of 101.

I'd like to see those exhaust results assuming they're for OBDII cars. Not one roller station here will allow an OBDII car on said rollers since the operators have no clue how to set up the software for a car that's not in their database.

We have a nice lab where I work but we have no methodolgy for measuring auto exhaust gases, merely vent gases off refinery-type units. No NOx and only simple hydrocarbons up to hexane so no PAHs or carbonyls or hydroxyls, etc.