Thanks for the info guys. Unfortunately, I'm not tuned yet. I took some time this weekend to shorten one of the defoulers but now the O2 sensor is a bit too long for it. The sensor bottoms out and basically blocks off any flow past the sensor. I have to get a 9/16 drill bit to enlarge to hole a bit more. Thank goodness the thing still runs fine because this is more than enough headache as it is. It's a work in progress I guess.

I've read through some other threads about these headers and it sounds like some folks add a different catalytic converter back in, behind the Y it sounds like. Would doing something like this help me out with this problem? Even if it doesn't I still may consider it so we can actually use the back window again without being choked out by the exhaust. The smelly exhaust is a predictable result that never really occurred to me.

I've been thinking about my problem with the sensor bottoming out in the spacer and I'm wondering if anyone has any non-OEM sensors to recommend that may be a different length. I see that NAPA carries a Bosch sensor that is shorter than the OEM. With the current sensor/spacer combination I have, there is very little room for adjustment.