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High Flow Cat = Less Responsive Than Standard Cat.

Munkyb0y

By Munkyb0y,
in Engines & Forced Induction

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mokompri Community Regular

mokompri

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I would expect the car to require a re-tune, may explain were some of the power is going. I would expect it to be running richer than before....

although a retune isnt *necessary*, i agree with you. a more free flowing exhaust causes an increase of airflow, which gives a higher voltage on the afm for the same load and rpm, which then means your hitting different cells on the fuel maps = running richer. same thing happens on sr20's

This topic has been a matter of contention before. You should gain power from increasing flow but in some cases you will lose some responsiveness in the trade - by this I mean the car will not feel as quick to respond to your throttle inputs but will pull harder once it does. Is this how it feels or are you saying it just feels worse all round?

In my old car I described the sensation as feeling the engine was not as 'tight' - as a stock RB25DET feels quite tight and zippy on the throttle response but you lose some of that feeling with a full turbo back exhaust with the obvious benefit being more pulling power (especially at higher revs).

an exhaust which gives you more power up top, means that it flows better then the previous/stock exhaust. flowing more up top, means it flows better down low as well, its not selective - and with less back pressure response and power is always increased, no matter where in the rev range. the lack of zip is probably associated with the richer afr as explained above.

Munkyb0y Grand Master

Munkyb0y

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if i do an ecu reset, i guess whatever the unichip is doing wont be adversly affected?

i know the timing is retarded, but i dont wanna mess with it without looking into the unichip setup, as the unichip does control timing as well as afrs.

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