With a cat that new, it should pass IMHO.
Try retarding the timing ot 0°. It will be down on power a bit, but it should pass with flying colors. Don't tell the emissions test people that you did this, they don't wanna know. Set it back once it passes. Good to go.

I would only try this if you were borderline- allowed 1700ppm, failed at 1800ppm. If the failure is like double the allowed limit, this will help but probably not get you into compliance. Something else is wrong then and you need to fix it. Could in fact be a failed cat- a lot of times this is caused by running very rich or misfiring, putting raw gasoline into the converter. They tend to melt inside if that happens.

Good luck with it!
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 234K, '82 245T/M46-182K, '84 242DL/AW70-100K, '89 244DL/AW70- 212K and I miss my: 86 244DL 215K, 87 244DL 239K, 88 744GLE 233K, 88 244GL 147K, 91 244 183K