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STI Uppipe decat versus Cat

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Old 27 July 2007, 06:08 PM
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feRRetboy
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Default STI Uppipe decat versus Cat

I just had to replace my Turbo and Uppipe after only 28k miles on a MY53. Part of the cat has melted and gone through the Turbo and fused the ceramics in the turbo and pipe.

The exhaust system from the Turbo backwards is all de catted. Since the uppipe that has been replaced is standard, i was wondering if i would be better fitting a decatted uppipe to remove the possibility of the same happening again.

Emmisons aside, would the Car be better or worse off with a de catted uppipe?

Old 27 July 2007, 06:16 PM
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Granby
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One of the first mods i did was to get rid of the uppipe cat for that very reason, should also help the turbo spool a bit better as the is nothing blocking the exhaust gases
Old 27 July 2007, 06:23 PM
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Mark'sWRX
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I've removed mine and was led to believe that not only does it let the turbo spool better but also lowers gas temps which is better all round. I've also heard that the cat is only there to lower emmisions when cold so wouldn't affect the MoT readings.

I'm not sure whether you'd need it remapped or a CEL light fix to stop the warning light coming on though.
Old 27 July 2007, 06:27 PM
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53
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Doh, much much better. I went for a decat uppipe made by H&S with a smaller internal diameter of 45mm.
Old 27 July 2007, 06:27 PM
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thats an interesting point about the light coming on. First of all am i right in saying that a prodrive ECU is self learning anyway? ( i forgot to mention i had the PPP) not sure about the warning light? To be honest the light came on after the damage was done anyway, i am going to add a defi exhaust temp gauge. maybe i can have that warning light took out of the error codes that get reported back? just thinking out aloud, it may not be possible
Old 27 July 2007, 06:31 PM
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Originally Posted by 53WRX
Doh, much much better. I went for a decat uppipe made by H&S with a smaller internal diameter of 45mm.
Is that the standard H&S size as i've had mine on for nearly 3 years and don't know what diameter it is
Old 27 July 2007, 06:39 PM
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No Zak recomended I ask specifically for a smaller ID, and he is the man. At the time I was also adding a sports cat DP to my 53WRX PPP, before his remap. I wanted to make the best of what I had without changing too much other than exhaust parts. It made 235 WHP and I think the smaller uppipe internals kept it running more effectively for what I was trying to achieve.

Interestingly I did not need a CEL fix having changed these parts.



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