Originally Posted by Kastley85891
Yes they will be off, you will be leaner on gauge then you actually are running. I usually just target my AFR regardless TBH, pre or post cat placement.
I'm not bashing your thoughts at all, but if that's the case then why is it that many tuners will hang a WBo2 on the tailpipe when tuning a car? The a/f reading would be all the same to the tailpipe wouldn't it?
All the molecules are still in there aren't they? Some may be broken down, but the sensor would still recognize them, would it not? And if that's the case, why would subaru put it there from the factory? Furthermore, wouldn't the up-pipe cat also throw the reading off?
That aside, to the original poster, I have no cats in my system, so even if that were true, my reading would still be un-skewed.