Who's running a De-Cat??

R

Rob84

New Member
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Hi ya,

Just wondered out of interest how many people there are who have changed the exhaust and have also replaced the CAT with a de-cat pipe??

And if you have which de-cat pipe did you get?

Cheers

G
 
I'm running a Toda manifold, so the decat is part of the system.

However, it's just a straight bit of pipe with 2 flanges and a couple of threaded holes for the sensors; not too tricky for an exhaust place to knock up.
 
Oh right I see. Do all manifold replacements include a straight through pipe to replace the CAT? I've just fitted the Mugen exhaust so might be tempted with the Mugen manifold if it replaces the CAT as well. (I thought I'd have to do both bits seperately)

So how does it stand with emmissions etc if you remove the CAT or has no one worried about that yet as we're not at MOT age??
 
It's not so much that they include a decat pipe, as often the manifold will be a slightly different shape to OEM and hence the link pipe will be specific to match up to the OEM catback "point" (i.e. the meeting points between various parts of the system are pre-determined to ensure compatibility - manifold-block and manifold-catback).

It's pretty much guaranteed you won't pass emissions, I've got another 18 months at least before this becomes an issue. When that time comes either you refit the OEM system or find a friendly MoT station.
 
So given the price of decent mods and the small gains made surely a de-cat is a very cost efficient mod but nobody seems to mention it much.Does it not give decent gains on the FD2?
 
in terms of decat effectiveness it would depend on how restrictive the standard cats are. Anyone notice a difference with a decat?
 
I'm guessing that there probably isn't a huge gain in performance. I reckon Honda know a thing or two about exhaust systems and how to get the best out of it (even with a CAT fitted) Lets face it 120BHP per litre ain't bad, so the stock system can't be that restrictive!

It would hopefully make a bit more noise though which is what I'm after. Can anyone confirm this?
 
I think you'll be surprised at the difference. Mine revs a lot more freely, especially at the top end.

While Honda do their best, they're still bound by quite punitive regulations, so the cats are still relatively restrictive compared to not having one at all!
 
Cool - an added bonus then. Unfortunately I think I'm going to have to wait a while before I can get a De-cat.

Having just bought the Mugen Exhaust, AST suspension and about to buy 4 new tyres I'm all but spent out! :-(

Unless anyone has one going cheap! :-)
 
Unlike the DC5/EP3, the manifold and cat are split.

Hence if you only want a decat, a good exhaust fabricator should be able to make one for a reasonable sum.
 
I'm running de-cat. Have a CPL racing manifold and de-cat pipe
co reads 0.78. Max allowed for MOT is 0.20. Hydrocarbons are fine only 27ppm
but these are not affected by lack of cat.
MOT not due to Feb 2011 so will put cat back on then.
 
Did you notice much difference over the stock CAT? Which back box and b pipe are you running?

Is it worth it from a noise point of view??
 
Removal of the cat will give you more power, as I had the ecu changed, the exhaust manifold and gruppe-m air box
all fitted at the same time could not give you an answer as to the difference. I,m running a standard exhaust from the decat pipe back, was told by Guy at CPL racing that the stock exhaust was more than adequate and if I changed it would be only to make more noise !!! The air box has wonderful induction noise and have not noticed any more noise from the exhaust, a cat is not a silencer just a filter.
 
Do those of you running de-cats have the engine management light on all the time requiring an O2 simulator to be fitted like the EP3 type r or does it not effect it at all? Just wondering if i'll need to get anything else for when i fit my toda system as don't want management light on all the time!
 
If you don't fit a hondata ecu then you will get the eml on all the time. I belive both the hondata and flashpro are designed so as not to switch the light on.
 
Just ordered my Flashpro this morning so that was handy! 😉
When you say they are designed not to switch the light on do you mean for anything or just for the cat sensors?!?!
 
this thread just reminded me - a few weeks ago John got one of his suppliers to make up a decat pipe for me - its sitting behind me in my study (doh!)..

I'll post pics of it later before I get it fitted.
 
Its to do with the lambda sensors, there are 2 fitted, one pre cat and 1 post cat. (but in decat pre decat & post decat) The hondata or flashpro are set so that the emissions reading post cat (which will be incorrect i.e. too rich) will not turn the eml on. The eml will work as normal if you get any other fault and will record the fault on the ecu which can then be read via the obd socket.
 
finally got my decat pipe fitted. Couldn't give it a serious test coming home due to the weather/traffic etc. but noise wise isn't that much different really but its woken up the engine slightly. In vtech mode it doesn't seem to labour so much and I'd say it spools up a little quicker. Will do more testing when I have grip!

I think John can get more decat pipes made up if anyone's interested?
 
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