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Discussion Starter #1
Sorry to bore you fellas, but I'm about to replace the cat. So, just a couple of questions as I've not yet crawled under the car to have a poke about.
a) Can the cat be replaced with a basic bit of straight pipe, or does it have flanges (!) on it which mean I need a specially made 'cat replacement pipe' - If the latter whats the best place to get one (Evo 1)
b) There is a cat sensor on the dash (Although it never warned me about tiddles when i was backing out of the garage-eek-splat) How do you bypass this, do I need to ?

Alternativly, is there a decent company I can bug about this ? Who are local-ish to me in North Yorks.

Thanks in advance
TonyC
 
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Discussion Starter #2
Tony,

I would imagine depending on what exhaust system you have at the moment ,you would have to buy an aftermarket job.
I know that on my mongoose all the gaskets from my standard system fitted the mongoose.[the holes etc lined up ok].
De-cat pipes if like stainless systems tend to be 3 -3.5 diameter,which may be a problem fitting straight onto a thinner piping.
A good welder could take the flanges off the cat and weld them to a straight piece of scaffold tube if necessary.
The cat sniffer on the cat box isn't a problem ,just leave it un connected as the main sensor [lambda] should be up around the manifold area ,monitoring emissions.the sniffer is only there to check if the cat is breaking down and not doing its job.No lights should come on in the dash.
Try links page for suppliers,mail order for most applies.

cheers

Paul s
 
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Discussion Starter #3
Tony,
The first change I ever did to my Evo I was to remove the standard down pipe and cat and replace it with a 2.5 catless pipe. This was made up at my local muffler shop and the bends were press bent (not ideal - mandrel is much better)but there was a big improvement in power and spool up none the less. I have since reolaced this down pipe with another local muffler shop 2.5 pipe, but this time the main bend is a stainless steel mandrel bend that I got from road/race engineering in the USA. An improvement over the previous setup but not nearly as dramatic as the change between the standard setup and the press bent one.

I would recommend you go this route instead of just replacing the cat. Oh for the temp. sensor on the cat, I just had them put a fitting on my down pipe to screw the sensor into. Not sure if this was even necessary though.
 
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Discussion Starter #4
Right, thanks fellas.
I can easily get hold of race shop exhaust piping of all sizes and bends (proper gas flowed curves). So I shall look at that route and go the full bend (!) The rest of the system is currently standard - but in such good nick I can;t find it in my heart to replace it all yet.
From your description Wreckleford I presume you've bypassed the flanged mount on the cat as your pipe runs down from the manifold.
After scrabbling underneath yesterday and getting thoroughly fed up I think my best bet it to pop down to my local friendly exhaust man and get it on his ramp and see what we can do now I'm fully armed with info

TonyC (And I promise I won;t aska bout exhausts again)
 
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Discussion Starter #5
Tony,

Let me know how you get on - I'm looking to do same mod for my EVO 1 RS.

Thanks,

Mark
 
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Discussion Starter #6
Will do Mark, I'm getting it done sometime this week so I will re-post.

Interestingly I spoke to Co-ordsport about this and they told me that the cat is very, very restrictive and I should gain somewhere in the region of 25-30bhp !

To be honest I had to take that with a pinch of salt but after speaking to a few other people it seems removing the cat should gain around 12% more BHP on any car - which is around 25-30Bhp on the Evo 1 engine.

I can't wait to find out if it is true


TonyC
 
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Discussion Starter #7
It certaily is a noticeable difference, but not 25 - 30 bhp. Prpbably more like 10 bhp in my opinion.
 
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Discussion Starter #8
Yeah, thats more the kind of figure I expected to gain.
Anyway, can;t complain about an extra 10bhp can you ?


TonyC
 
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Discussion Starter #9
I remember when the cats were first introduced - they knocked the 130bhp 205gti down to 122bhp. Removing the cat and fitting a better down pipe has to be worth more than 10 horses.

Cheers,

Mark
 
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