The CA 99 manifold contained a cat, aftermarket header installed now. Do I need both sensors hooked up at the top and bottom of the header for my new MS2?

Searched but didn't find an answer.

Appointment in another city for tuning (trailer trip) and two days of racing this weekend.

My mechanic is waiting on the harness extension kit but if i can skip it I can still keep the project moving.

Thanks for your help for this pitiful Noob.

 

Neither O2 sensor is needed if you don't do anything closed loop. You will need a wideband for tuning the MS2 though.