Ok, I tried searching but maybe I'm not trying the write words. Here's my case..I just purchased a 93 HB w/ a DOHC ZC in it, has a header, intake, 2.25 exhaust w/ an ES tuning muffler. I replaced the cat because it had a straight pipe originally.
After only 10 miles on the new cat (didn't know there was a break in period) here are the results from the smog check: http://pg.photos.yahoo.com/ph/...rc=ph
Here are the results after 110 miles on the cat and rxp additive to the fuel (89 octane gas in there): http://pg.photos.yahoo.com/ph/...rc=ph
SO I'm doing better on my HC count, but my NOX is double what it should be.
Anyone have the same problem, anyone know what I can do? I thought about replacing the O2 sensor, but it's not throwing codes, what about retarding the timing a bit (set at stock right now).
Thanks and I'll be forever in your gratitude oh mighty HT members.

Vic