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Discussion Starter #1
I bought my car with the cats removed, in their place is a fabricated midpipe, with the O2 sensor in the LH pipe, meaning that it's only sampling the exhaust stream from 3 of the cylinders. Does the stock midpipe with catalytic converters present, have any type of crossover such as an x- or h-pipe in it? Is there any advantage to an x or h pipe on these cars regardless of the O2 sensor question?

Thanks!
 

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yes there is a crossover so the 02 sensor gets a sample of all 6 cylinders.

I believe stock is an X type of crossover. I have a fahey track pipe and he uses an H style (but that might be just because it's easier to fabricate). IIRC, there are some theoretical differences in torque production, but i can't remember what they are. On my euro car the o2 sensor is right at the X.
 

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Discussion Starter #3 (Edited)
Mike, thanks for the reply. That's what I had suspected from seeing pictures of stock exhaust systems.

I took the car to a local exhaust shop, they cut out a portion of the pipes and welded in a pre-fab x-pipe. The O2 bung is in the side of the X. I also installed a new Denso O2 sensor. Seems to be smoother, though that could just be a loss of the resonance that was occurring from the straight pipes running so closely together.
 
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