Primary heated O2 sensor heater circuit fault ( sensor 1 ) was replaced, code 41 vanished and followed by code 67, Catalyst system efficiency below threshold.
Honda Dealer would replace a cat for $1,200 plus labor, shop supplies, etc and taxes.
High flow cat or a resonator does not come with O2 sensor fittings.
Has anyone installed a test pipe on OBD-II CIvics without hooking up sencondary O2 sensor?

2000 Honda Civic EX

 

dont do a test pipe. itll trip CELs all the time. also, you can find a high flow cat for WAY less than the stock one.

 

Catco made a highflow catalytic converter PN# 4839 for Civic Si.
Do you know of anyone using Catco highflow converter or othr brand with a good result, perfromance without check engine light on?