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Old 07-06-2009, 11:29 AM   #8
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Xanthos's Avatar
Drives: Formerly-Stick
Join Date: Mar 2008
Location: Oklahoma
Posts: 12,588
Originally Posted by mr_desmo View Post
Thanks, thats all i needed to know , the car runs rich for the cats to do their remove cats get the car tuned ,be done. next add nitro, race 997tt have fun
No. You missed the point - direct injection engines go into a lean burn mode when cruising on the highway; thats how they get such good gas mileage on the highway.

If you were to remove the cats, "getting the car tuned" would have to include "tuning out the lean burn mode" which wouldn't be possible with a piggy back system, and thats all that it looks like we'll have for a while (the cobalt SS guys haven't even been able to crack this box yet, and they've had ahold of it for a while now).

So, its either high-flow cats or spit out huge amounts of NOx. Hopefully you don't have emissions testing.
- X

P.S. - And if you were to tune out the lean burn mode, it would absolutely cripple your gas mileage. Lean burn mode can account for a 25-30% improvement in gas mileage, so you're looking at an 8 mpg drop or so.

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