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GTROC NOBODY
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5,981 Posts
Discussion Starter #1
Just out of curiosity,
Why are de-cats the same size diameter through?
Cats are normally bigger after the flanges, which i pressume is for expansion.
Does anyone make a de-cat that tapers from the flanges to a bigger chamber, or is it just not necessary.?
My reason for asking is that soon i will be fitting a new exhaust..large dia, but my Apexi downpipe is 80mm dia I/D and the decat is 75mm I/D. Would it not be better to have 80mm I/D entry and something like 150mm chamber?

Thoughts?


Paul.
 

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2,580 Posts
Hi Paul,

Is this the answer? Taken from the Abbey Motorsport site;)

Big-Bore Catalyst Replacement Pipe



Catalyst replacement pipes are available from many sources, however we have never found them in a suitable bore to maintain the correct sizing all the way through with some of the larger Japanese exhaust systems, our catalyst pipe is physically the largest possible pipe that will fit behind the flanges, while still allowing the fitment of cap-head fasteners. The flanges each end are laser cut and TIG welded (Not MIG like some cheaper cat-pipes) and are constructed of 304 Stainless Steel throughout. As a final convenience our cat-pipes feature a center bung for standard (NTK, Bosch etc) wideband lambda sensors and a bossing for the standard exhaust overheat sensor.

These pipes are available for all model GTR's, most GTS's and GT-T's, please specify when ordering.

Regards,

Dave.:)
 

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GTROC NOBODY
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5,981 Posts
Discussion Starter #3
Thanks Dave,
Well i guess that answers my question, but would still be interested in the reason behind it.:rolleyes:
 
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