I installed my AMS High Flow Cat. My SES light came on. I was sure it was because of the High Flow Cat. I check it just incase it was something else. The error code was for an exhaust leak near the rear O2 sensor or bad O2 sensor. So I ordered the O2 Sensor Spacer from AMS. It comes with 3 different jets. I wanted to know if anyone has used it on the X's yet and what jet was used to get rid of the SES. Really dont want to try every jet to figure out which one will work if I dont have to. Thanks in advanced.

 

I'm not familiar with their O2 sensor spacers, but I would use no jet at all - or maybe the largest jet - since you indeed do have a cat and you want as much exhaust gas to reach the sensor as possible.

Just a warning, though... using this may cause you to get a slow O2 sensor response code.

 

I'm running AMS's test pipe with spacer.

I didn't use a jet, didn't think I needed it, no problems, no CEL.