Milltek Hi-Flow cat vs OEM cat pic from weekend install.
05-01-2007, 05:33 AM
#7
Interesting position of the stock 2nd Oxygen sensor compared to the Milltek.....
With the stock 2nd oxygen sensor in front of the main cat, it appears that the main cat is not involved whatsoever in ECU feedback regulation, only the pre-cats. Compare this to the Milltek where you have only one cat, and a pre and post cat sensor as one would expect.
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05-01-2007, 06:27 AM
#9
My comment was more about the fact that the stock downpipe DOESN'T have a post-2nd cat sensor...
This would seem to imply that in the stock configuration, only the first cat is involved in the ECU feedback mechanism, and that one could dump the second cat entirely from the stock exhaust without triggering a CEL?
05-01-2007, 07:44 AM
#10
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Umm, it usually is only the first cat involved in the feedback mechanism.
But your comment about dumping the second cat without triggering the CEL is correct. Having said that, why would you want to retain the front cat that is so close to the turbine outlet? Better to get rid of the first cat and move the second O2 sensor behind the second cat.
