If you are gonna strictly run the reflashed ecu......no. it is a fixed map with no adjustments being made by the ecu. If you will be using an autotune hooked into a power commander.....then yes you will......because it will see the A/F and make adjustments accordingly.
The stock O2 sensor is narrow band. The O2 sensor that comes with the autotune is wide band.
This is what Tim told me when I called him the first time. 80% of everyone that gets the Ecu reflashed will be very happy with it. The other 20% will want it to be perfect and so will go with the power commander 5 to be able to tune it all the way.
Now that being said......the pcv only gives percentages. So.....unless you on a dyno......you dont know what the air fuel numbers are. Now......with the autotune you can say that I want a particular air fuel at a certain rpm and throttle position. I also run the pod300. Which is a gauge that can be configured multiple ways. I have configured for air fuel and throttle position. This way I can see what is happening at all times. For instance......at 15% of the throttle and 4000 rpm what I have the autotune set at......the bike likes......but it doesnt like it at 20% throttle.
Also......sometimes the autotune will give a positive fuel number in one cell.......and negative.....taking away fuel in another. It's easy to see things in real time using the pod300.