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I installed a catalytic converter on my Miata powered series 2

Toyanvil

Toyanvil

Gold Level Sponsor
A couple of week ago I installed a catalytic converter on my Miata powered series 2. As to the why? the Miata motor uses a one wire o2 sensor, so no heater in it, it needs the heat of the cat to work better. And it helps the air quality. Here is what I have learned in the last couple of weeks, the car runs a lot smoother ( at idle the shifter has almost no vibration) I love the quieter throater sound ( it no longer sounds like a kids tuner car) and it has no smell out the exhaust pipe. I have not found any down sides. I know there are more Miata powered Alpines out there that this may help. The cat installed is a universal Magnaflow.
IMG_6175-XL.jpg

Heat shield installed
IMG_6195-XL.jpg
 
DanR

DanR

Diamond Level Sponsor
Do you have a specific part number available? I may have to add one OR two to my Red GT V6, if and when I ever get it running.
 
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B

Bill Blue

Platinum Level Sponsor
Dan, better change that statement to "I may need to add two to my Red GT V6". Although I co not understand how a convertor would make the engine run better. Once again, time to educate the Old Man. Is this a situation where a dab of back pressure eases the impact of a poor tune?
 
Warren

Warren

Bronze Level Sponsor
"No longer sounds like a kids tuner car."
Bravo

I'd guess that F. I. Cars need some back pressure in the exhaust with any kinda stock chipped system.
 
Toyanvil

Toyanvil

Gold Level Sponsor
I believe the improved performance is from a little of everything, more back pressure and heat on the O2 sensor. I am using the stock ECU so there is no tuning and now it see what it was looking for. I now have the same exhaust set up that a Miata has and I already had the stock intake. I have been driving with the Miata running gear going on 8 years now, and I can feel the difference.
 
J

Joe-dick

Donation Time
You're smoother running is likely due to more accurate feedback from the O2 sensor rather than a change in exhaust flow or pressure.
The cat is a pretty effective muffler though.
Ages ago I had a customer come in with a full size late seventies Pontiac. Someone had removed the catalytic convertor for him claiming it would give giant performance gains. Instead he gained an undriveable (to him) car because of the excessive noise. He wasn't too crazy about the price of a new cat so I installed an additional muffler where the cat should have been and he was happy.
Joe
 
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