WTB Catalytic converters for 99

[REBible]

I am looking for a pair of cats for 99 boxster. I failed smog and need to pass, so I need some with reasonable mileage.

If anyone has a clue as to cause, I am interested. Car is well maintained, no oil burning, oil separator changed before failure... no alarms, runs good. Engine data on duremetric looks good fuel trims are as expected,,, also used snapon fancy dancy scanner and other diagnostic tools etc... the post cat o2 sensor sure enough shows not much cat effeciency.
I do not know why it isn't alarming as like most porsche's it picks everything else up.

But when we put it on smog sniffer HC and NOX are off the charts. hc 150+ NOX 800+


thanks
robert