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Discussion Starter · #1 ·
Was wondering if anyone replaced their OEM Cat to high flow cat only in conjunction with OEM header and exhaust?

Will I likely to see more gains replacing the cat only then an exhaust?
I do like the looks of the Oem exhaust.

Any problems with emissions?

thank you :)
 

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How much of a difference in terms of HP and noise? As well did you have trouble doing emissions after the sport cat?
Thank you :)
I replaced the stock cat with a straight pipe.

Noise increase was significant, but I like it. Butt dyno says it is good for some extra hp, but how much is just a guess.

I used a Weapon R eliminator angle fitting (see pic) to trick the O2 sensor. No CELs or engine issues.

Emissions isn't an issue for me as my car is registered as a "Collector" vehicle in Ohio and as such is exempt from emissions testing. :coolnana:

Regards,
Wayne
 

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Monkeyboo

The problem with any exhaust/cat modification is the ECU. On all Elises and Exiges the adaptive ECU detects cerain alterations and adjusts to compensate for it.

Even if there was some HP to be gained from the high flow cat, the ECU will adjust A/F ratios, timing to basically prevent that.

To ever make the sport cat or an exhaust improve performance, you will need a custom ECU tune. Someone like CharlieX can do that but it will be as much, if not more, expensive than the whole exhaust itself.

If you search this forum, you will learn other pro's and con's to header, cat and exhaust changes. There are lingering fuel fumes, codes tripped and emissions issues (in some states) that you might want to be aware of.
 

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I run a Larini Decat and a CEL Eliminator from PEP boys ($3). No CEL lights or emission problems. Biggest difference is deeper sound, fumes, and improved throttle response.
 

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Have you thought about getting your header ported? According to a thread on 'Intakes and Exhausts' you will gain hp and not have to get a reflash on your ECU. I am just repeating what was said on that thread, as I have not had it done (although I have considered it).
Rick
 

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Discussion Starter · #9 · (Edited)
Thank you guys for all the wonderful reply! I will have to rethink about this one.

Also difference between De-Cat and Sport cat, would this be Night and day interms of performance???
 

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I've got the Larini sport cat with the stock exhaust. Sound remains close to stock and no CELs. Car seems to have slightly more torque. I daily drive my car and can run in high gear at times when I would have downshifted before.
 

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Sure. They are dyno proven to do nothing.

The only thing they do well is break apart. They have a much shorter shelf life than typical OEM supplied catalytic converters.
 

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It was so long ago in the DSM community, I doubt I could find it. It was on a site called MitsubishiUnited.

It's a pretty universal opinion though, so I'll just google it.

I just googled it, and couldn't find what I was looking for, so I'll just explain it myself.

The reason it's a 'high flow' catalytic converter is because it simply has less material than the OEM one, thus increasing the flow. So what? Well that means that the cat won't last as long. If you have ever removed a cat from a high mileage car, they weigh a freakin' tonne and a half. So think about it, by reducing the restriction ever so slightly, what are you really gaining? I can tell you with certainty that it's in the tenths of a horsepower.
 

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Wrong info?

So, after reading the Tubular page on this, I guess the guys who said the ECU won't relearn and that sport cat does not do any good were wrong???

I almost thought no after reading their posts, now I'm back to considering.

Thanks.
 

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2bular is a quality product - absolutely, however reread what Jim (at 2bular) states on the site link above...

The Lotus/Toyota ECU will adjust, eventually.
What he means is any actual gain from the sport cat will be taken away by the learning of the ECU. This is just how it works. He then goes on to talk about some of the reflashes available. This is the only way you will get a gain from a sport cat.

The Gotham + 2bular tune is what - about $1400 (goth.am webstore!) - so add that cost on top of the cat and exhaust. Then, according to Charlie, you should be good for about 240-250RWHP.
 

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I beg to differ that high flow cats don't work. If you can get away with running a test pipe, good for you.

But a high flow cat with (IE - 100 cell count vs. an OEM 500 cell count) will produce a very different exhaust output flow.

Also, the difference between having a cat and no cat in practicality is only 1-3 bhp increase. Anyone can argue, that itself is pointless.
 
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