which would be the best as i think they do the same 1/ apexi s-afc II or 2/ afr gauge and a knocklink

 

The SAFC II is a fuel controller with combined knock sensing whereas the AFR is an Air Fuel Ratio meter(Display Only). It depends really if you only want to display AFR or actually change it?

 

sorry worded wrong i know the s-afc II is a controller but can i still use it as a visual gauge to see if i run lean or rich also the same as regards to the knocklink( or would i have to buy all 3 to be able to do this)

 

The SAFC II doesn't display AFR according to the documentation but only correction values as it uses the Air flow sensor signal not the lambda signal, it does have knock detection though. I personally have a Knocklink and a Lambdalink However I do have an APEXI SAFC piggy-back fuel controller which I may sell as I do not use.