The two codes are related.
Are both of your O2's still installed in the exhaust? If so, you need to pull the second one out and just plug the hole, or any of the other tricks that become necessary when you remove the cat.
Or, you could get a high flow cat and probably be back in business.
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-Harry
AIM: NDcissive
CRX and Pre '92 Civic, Engine Tech and Tuning, & Track and Autocross Forum Mod