Exhaust: replacing the cat with a resonator

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MrGrey
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Exhaust: replacing the cat with a resonator

Post by MrGrey » Thu Apr 04, 2013 12:49 am

Hello again,

My 1990 NA6 still has the catalytic converter installed (it has been replaced once, before I bought it). Now I would like to replace it with a resonator which I assume is the the correct action to take in this case.
Which leads me to a few questions:

1) am I right in understanding that doing this will increase the volume of the exhaust? (I am all for the free flowing of exhaust gasses but I am mindful of my volume, no need to draw attention to myself whilst driving)

2) will I have any hassles getting a WOF? ie, do we have emission standards requiring I have a cat?

I have read that in the UK (where their emission laws are pretty rigid) that you don't have to have a cat on a 89/90/91 miata due to their age and was wondering what the deal is over here. Is the only check for emissions when he checks your exhaust smoke amount and that's about it? or should I just leave the cat alone?

Thank you in advance

WideOpenThrottle
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Post by WideOpenThrottle » Thu Apr 04, 2013 8:18 am

My 89 doesnt have a cert & if you read the new laws then most cars up to anything registered before 2010 doesnt seem to need to have one.

http://www.lvvta.org.nz/documents/stand ... ssions.pdf

Open to interpretation as always.
1989 NA 1650
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warrior
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Post by warrior » Thu Apr 04, 2013 11:32 am

100% legal on your car, wont be much louder at all.
warrior

siren676
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Post by siren676 » Thu Apr 04, 2013 12:12 pm

I did it recently on mine, just got the cat replaced with a coby that was the same length and had some flanges put on that.

Seemed to rev slightly more freely and removed a buzz i had around 3-4k rpm
1990 NA6C MX5

authentic
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Post by authentic » Thu Apr 04, 2013 3:24 pm

I've passed a VTNZ WOF's with this abomination from a 'professional' muffler shop, no questions.

Image

Before that I had a coby with a stock system and it was sweet. Sounded completely stock. A test pipe would increase volume but a proper resonator will keep it low key.

siren676
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Post by siren676 » Thu Apr 04, 2013 4:24 pm

:shock: Did a monkey to make that?

This is my one
Image
1990 NA6C MX5

MrGrey
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Post by MrGrey » Thu Apr 04, 2013 5:07 pm

thanks for the replies and pics =)
siren, I had to take a double look at your because its paintjob made me initially think "errrr its not supposed to be red hot"

I think this will definitely be next on my list after some new tires before the WOF is due next month =) how much would I expect to pay to have this done? $60-100?

authentic
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Post by authentic » Thu Apr 04, 2013 5:44 pm

I just wanted the cat-back fitted and a test pipe fabricated since the old midpipe was one piece from the headers to the axle. The flange bolts must have been stubborn because he cut and welded the cat delete pipe on instead. I don't know why he bent the shit out of it though.

You may have luck finding a direct bolt-on one on mx5mart.

siren676
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Post by siren676 » Thu Apr 04, 2013 6:58 pm

Mine cost $125 from counties mufflers in pukekohe
1990 NA6C MX5

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