There are a few options to pass emissions without integrating cats into the exhaust:

1) Use the euro tune that will suppress the check engine light, but this will only work if your state doesn't require all OBDII monitors to be in a "ready" state.

2) Some have had success using spark plug anti-foulers/o2 sensor extensions that put the after-cat o2 sensors out of the direct exhaust stream keeping their readings within tolerance.

3) Use real o2 simulators for the after-cat o2 sensors to mimic the correct values the ecm is expecting

4) I don't know if anyone has done this successfully yet, but adjust the parameters for the after-cat secondary o2 sensors so that they'll accept any value without impacting monitor readiness.

For me, this is one of those "cross that bridge when we get there" situations. I've done a lot of tuning on GM cars to this effect and am hoping the same can be done here. If all else fails, it's re-install the factory manifolds every other year - tho yuk.

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2012 xDrive35d
2001 BMW X5 3.0i 5MT
and two 1987 Corvettes - Callaway Twin Turbo and Guldstrand Grand Sport 80
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