I have an 08 spec-v as well with a megan header in it. My SES light comes on sometimes as well but I have only spaced out the o2 sensor in bank 2(which is the one on the right side). I have been able to drive for roughly 1000 miles before the light came on before. It comes and goes to tell you the truth. I am going to try and space out the other o2 sensor to see what happens. In my spec-v, the upper two sensors are actually air fuel sensors while the bottom two are heated oxygen sensors. Not sure what djtorello is talking about tho. Also before I spaced out any o2 sensors I was just getting code p0430, which is the code saying catalyst efficiency below threshold, bank 2. So I spaced out just that one sensor. Now when the SES light comes on I get codes P0430, AND P0420, which is both bank 1 and bank 2 sensors. I will try to space out the other sensor to see what happens. Might have to try an o2 simulator eventually.