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Hi all. I had my original (I didn’t know the scrap value of these and that the car was a target) catalytic converter unceremoniously chopped from my beloved 1992 Miata N/A. See aftermath pics. Can anyone please advise next steps to get the car functioning again and who can help fix it (exhaust place?, normal garage?, mobile mechanic?) . I know that I have the option of an aftermarket (no scrap value) cat. Will that go straight on? I doubt it if the ****s have cut before and after the cat. Should I just go for a full replacement system that will improve her performance?. And approx costs ? Apologies for ignorance/ my lack of knowledge on this. Many thanks in advance. Much appreciated Richard
 

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Hi Richard

Sorry to hear about your predicament. There's a couple of ways to skin a cat as they say.
Yes an exhaust place would be the easiest and quickest route, but easily the most expensive, how much can and are you willing to do yourself?

I am unsure of the rules around imported American cars in the UK (you say you have a Miata) - I know that Japanese cars of this age don't even need a cat to pass the test, and UK registered ones before 92 don't but unsure where the cut off point is.

If it were me, I'd probably do something like you have suggested and just get a new downpipe, cheap cat bypass pipe and cat back exhaust. Use it as an excuse to get something nice.

Costs if you can fit yourself, £300ish for a nice catback if brand new or £100ish used, £100 for a nice manifold if you buy used or £400 for a nice new one... and £50ish for a cat bypass.
 

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I think 92 is the cutoff year in the UK for Cats. If they were fitted from the factory then they should be present for the MOYT, however I did find this through a google search and if yous is an import you should be fine without a cat.

Spark ignition cars first used on or after 1 August 1992 are subject to a Basic Emissions Test (BET) regardless of whether a catalytic converter is fitted or required. In the event that the BET is failed, it becomes necessary to reference both the MOT Inspection Manual, Section 7.3 and the In Service Exhaust Emission Standards for Road Vehicles publication (Emissions book). The MOT Inspection Manual is available on-line at http://www.motinfo.gov.uk/htdocs/ 32 and the Emissions book at https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/194133/Emissions_17th_Edition.pdf 74

For vehicles first used between 1 August 1992 and 31 July 1995, if there is an exact match for the vehicle in the Emissions book, then a full cat test must be carried out. Where this is the case, the vehicle must have a catalytic converter fitted or it will fail, regardless of the result of the emissions test.

If there is not an exact match in the Emissions book, then the vehicle will be subject to a non-cat emissions test (two gas test). Where this is the case, the vehicle is not required to have a catalytic converter fitted for MOT purposes, regardless of whether one was originally fitted.

I am unable to provide an answer specific to a particular vehicle as you have not provided any details of such. However, assuming you have the relevant Vehicle Identification Number (VIN), you can easily check for yourself using the link to the Emissions book and referencing page 70 of Section 1 (page 86 of the pdf). The Mazda VDS number is the 4th to 9th digits of the VIN.
 

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Sorry you've had this aggravation.

A replacement cat would come with bolt-on flanges front and back, but your photo seems to show the thieves have cut off those flanges, taking a few extra inches of pipe on either side. So your options seem to be either to get an exhaust place to weld on new pipe and flanges so they can bolt in a new standard sized cat, or to let them weld in a generic cat with plain pipe ends. The latter option is probably cheaper. You have a third option as your car is a grey import Japanese Eunos Roadster (according to your other thread) rather than a North American market Miata; you could just delete the cat entirely and have them weld in plain exhaust pipe. That's okay for any car up to J-reg which might include your 1992 model, but not for K-reg unless it has a specific exemption. Being a Eunos Roadster, yours will have that exemption.

If you chose to delete the cat be aware the car will be louder and the exhaust smellier. Happily, even the cheapest of aftermarket cats will be more than adequate as your car only needs to pass a non-Cat emissions test.

One other little detail is that Roadsters have a cat overheat warning lamp in the dash. It connects to a sensor in the side of the cat and your photo shows the broken end of the wire dangling down. (A replacement cat would not have the sensor to plug into unless you got a cat specifically for a Eunos Roadster which I guess would be prohibitively expensive.) Left like that the "Heat" lamp will be permanently lit in the instrument panel. If that bothers you I believe you can fix it by looping the pair of wires in the cable together. There's a plug under the car not far from the cat so you can unplug the short tail of cable. Then you can shorten it and separate out the pair of wires inside, join them and insulate the ends. That should make the Heat light go out.
 

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Sorry to read that mate, I know how you feel, we had a CAT stolen off a car last year, a Lexus hybrid. It's since been sold after it cost £2k to replace it under the insurance.

A few weeks later I then had someone walk up the driveway and look underneath the MX5, but then they walked off!

Out of interest is your car lowered? Mine is quite low but you can get some very low profile jack's underneath the sill. I'm wondering if that put them off. I have been thinking about decatting it and just refitting it for the MOT but on the NB I think it's going to be too much hassle.
 
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