One channel is ok but the 2 channel is best because with a 1 channel and dual exhaust you have to put the 02 sensor in 1 side or the other. If the side without the sensor goes lean it can't shut the nitrous off for you. Note, you can tell the 2 channel to default to the leanest channel. That way if one channel goes lean and the other channel is still ok it will shut the nitrous off.

I suppose is you have single exhaust & put the sensor down strean of the Y pipe you would probably be ok. Except if one bank goes lean it will not be as sensitive as a 2 channel because the richer bank would cause the sensor to read richer than the lean bank is running.

Check the FJO website and it will tell you all that it does.

The unit comes with 4 foot leads from the 02 sensor to the control box. I put the control box under the pass. seat and bought 2-8 ft. leads. I did not know you can connect the leads together to extend them. So if any one needs a longer lead I have 2-4 ft. leads for sale.