NA8 Cat Converter replacement

chrisd · Postby **chrisd** » Sun Mar 27, 2011 3:20 pm

I need a new cat converter on my 1993 NA8 :NA8:

. The current one rattles like a chain saw at 3000rpm

. Anyone have a good exhaust shop to recommend in Melbourne [ Brunswick/Fitzroy area or South Melbourne] :?:

Should I buy a new cat converter and get someone to fit it or just get it repaced? :?:

thanks

,
Emma

pcmx5 · Postby **pcmx5** » Sun Mar 27, 2011 9:25 pm

Emma,

Sorry not in Melb but a steel high flow cat should cost around $450 fitted and a Ceramic cat $100 or so less. We know from dyno time that a steel cat can give around 4 Kw more power at the rear wheels than a working but old original cat.

If your cat is really stuffed you will certainly feel a increase in power with a new one.

Good luck,

Peter.

pcmx5 · Postby **pcmx5** » Sun Mar 27, 2011 10:42 pm

Just looked on Ebay and Xforce steel cats are selling for $149, good buy.No way anyone should charge more than $100 to fit it !!

Peter.

93_Clubman · Postby **93_Clubman** » Mon Mar 28, 2011 12:38 pm

As Pete says, perfect opportunity to go for a high flow cat. Only other comment would be that it's common on NA6 & NA8 for an exhaust vibration to occur around 3k RPM, which is usually attributed to external exhaust heat shields at headers, cat, or bullet muffler. But if you've identified that it's def cat internals then go for it.

pcmx5 · Postby **pcmx5** » Mon Mar 28, 2011 12:46 pm

93 is right check everything.

Should have said that a steel cat will be a bit louder than a ceramic one but not too noisy, especially if you retain the standard exhaust.In fact I reckon the NA6 had the best exhaust note of any standard MX5 so this should sound great!

Peter

chrisd · Postby **chrisd** » Mon Mar 28, 2011 2:15 pm

thanks . I had the heat shields all checked and one re-welded. The repairer said it was the contents of the cat rattling. will get it checked first by whoever does the exhaust. The new cat converter needs to be for a 2" exhaust pipe to fit the NA8 ?

manga_blue · Postby **manga_blue** » Mon Mar 28, 2011 2:48 pm

Stock NA8 exhaust is 2". A good exhaust shop can flare the pipes into and out of a larger cat if that's what you want. A bad exhaust shop will totally bodgy it.
You may wonder about the condition of the rest of the exhaust system if the cat is shot.