would a high flow cat trip the o2 sensor thus resulting in a check engine light?

 

no, our cars are pre obd.

 

can u explain what that means..

 

If you have a check engine light, that means you have a S5. There's a way to pull the trouble codes from the ECU and see what it's complaining about, but I don't know what that way is (I have a S4, and a different way of pulling trouble codes).

The O2 sensor is before the cat, so there shouldn't be any way to mess up it's reading by what you do behind it.

-=Russ=-