[Jeph]

Here's what I would do if it were my car.

1) Replace the O2 sensor throwing the code. I think that would be easier than putting the old exhaust on.

2) If that doesn't fix it (or if you don't have time to do that), I would try some RXP. RXP comes in a small orange bottle and you add it to a tank of gas when you fill up. Drive with that for about half a tank and take your test.

I have used RXP twice, and it worked both times. Granted, this was with a 1994 Ford Probe GT, but here was my scenario. I went to get a state inspection and failed emissions. Put the RXP in and passed. Exact same scenario the following annual inspection.

It's about $8 a bottle, so perhaps worth a shot. Your local auto parts store should have it.