hey guys i got a 99 prelude and i wanna put a resonator/straight pipe on but the one i have doesnt have an O2 sensor on it.
do i need the secondary O2 sensor or can i do without?

 

obd2, you'll need the secondary O2 sensor or else you'll have a CEL I believe.

 

just convert it to obd_1

 

The short answer is no. The 2nd O2 sensor just tells the ECU that the cat is working properly. Without it, you will have a CEL though. Password JDM sells the bung that you need to weld in to install a seconday O2 sensor, or you could just buy a test pipe that already has the bung in it, all ready to go.
Either way, if you are getting rid of the cat, you'll need to do the non-fouler mod to the secondary O2 sensor. Search for it. I don't feel like explaining it. I've had too many beers for that much typing.

 

O2 simulator from O2simulator.com

 

Have you tried buying off there site... I have tried all day and it is impossible... I have try contacting the company to ask what to do but no response

 

just convert to obd-1 if your going to keep modding your car. stand alones work better obd-1

 

change another one