I just wanted to comment about an s-afc. I looked at getting one but after reading about it I decided not to and heres why. the safc works by modifying the maf signal to change the ecus reading of air intake and tricking the ecu into adding or trimming fuel. Well if you have want to lean out the mixture, the ecu will be reading a lower maf number and calculate that as a lower load on the engine. This will cause the ecu to actually advance spark timing, something (im my case of high compression) that I absolutely do not want to do. So if you are considering a safc by itself, I suggest that you look to a better setup becuase the safc will effect timing, but not allow you to control it. Id love to hear what other people think of this, and if I am on track or not.