HELP! Failed emissions in Ontario Canada, 91 LS

Hey all,

Just did the e-test today with full confidence and, lo and behold, my 91 LS failed. Numbers as follows:

Running test (ALL FAILED):

HC reading 80 ppm, limit 66
CO reading 0.63%, limit 0.37
NOx reading 3080 ppm, limit 757

Idle test (PASSED):

HC reading 137, limit 200
CO reading 0.74, limit 1.00

I’ve been told by a couple of different mechanics that it’s probably the catalytic converter.

Opinions here? I’m getting quotes of around 400-450 for a cat installed and with taxes. In the Toronto area.

Thanks.