THSCC Forums

In my efforts to squeeze more than 100 rwhp out of the Miata, I'm reworking the exhaust system this offseason. I have a 4-2-1 header and 2.25" stainless cat back so far. My next purchase will probably be a hi-flow cat con. Every last .5 hp counts on this car. At the very least, I'll be loud enough to convince myself I'm making more power.

Prices vary from $80 for a kinda-scary-lookin universal 2.25" inlet/outlet unit up to $250 ones from Jackson Racing and Flyin' Miata. My preference is to buy one that just bolts in to the stock location so I can do the install work myself. If a universal + labor to make it fit is cheap enough, I might change my tune.

Does anyone have specific good / bad experiences with aftermarket hi-flow cats? Recommendations on brands / vendors?

Man, it sure was easier to make HP with a turbo car...

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Tom Freeman
'98 M3/4/5 | '93 Spec3 325i | '12 TSX sport wagon | '03 Tahoe
Team Silver Bullets '91 240SX

Tom, this is the brand that I had on my talon and is currently on the mirage:
Dynomax

Scroll down until you see the one for $52.99. I'm sure that RJ&G can weld flanges on it, to make it a bolt-in.

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In need of car.

*cough* Test Pipe *cough*

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02 Focus SVT
STF 9

I'm by no means a tree hugger but, *cough* ILLEGAL *cough* ...

Magnaflow or their parent company makes high flow cats. Not sure on their quality but prices are pretty good. Best one out there that I know of is Random Technology. But they aren't cheap...

Graham

I've read on miata.net that the JR cat is not very durable, however the FM cat has received good reviews. I would check out the miata.net Product Reviews section for more info.

Jeff

Chevy truck cats. That's what I used on a couple of cars. I was looking for a 2.5" cat for a project and didn't want to spen a fortune. So one day I went into Advance and told the guy what I was looking for. Next thing I was back in the shelves with a tape measure looking at the various cats,both for inlet size and overall size. The one I ended up using came from a full size Chevy truck with the Z51 package. It was 2.5" inlet and outlet, stainless , and I could see through it. Oh yeah it cost $79 too

I went with a "catcon" or something like that over at R&J. It was one you could see straight through. The honeycombs were huge! I don't remember how much it was, but it doesn't look like it does much converting

-Tom

I believe the "hi-flo" cats are two compound matrix honeycomb as opposed to three compounds in the standard cat. Accounts for the typically lower pricing of the "hi-flo" versions.
Depending on the state of your car's tune, you *might* fail a tailpipe test with a "hi-flo" and pass with the standard version.
Or so I've read ...

Frank

Thanks for all the advice - for exactly the reason Frank mentions, I'm going to have flanges welded on this new hi-flo converter so I can swap in the original one in the event of an emissions failure next fall.

Depending on the price, I may have the shop make a test pipe for track- only use. I am somewhat of a tree hugger, even though my daily driver leaks oil like mad.

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Tom Freeman
'98 M3/4/5 | '93 Spec3 325i | '12 TSX sport wagon | '03 Tahoe
Team Silver Bullets '91 240SX

Just don't mix your tree hugging in with your track events.

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Not spectacular just decent.
I'm not sure what I'm driving.
Maybe an ITR in DS.
Or half-assed STX prepped 330.