AFC tunes fuel and timing maps by altering the airflow signal from the MAF. It does nothing more than that. It works to a point, but is not ideal. DSMlink allows fuel and timing to be tuned independently, also adds anti-lag, 2-step (launch control), flatshifting, solenoid controls, idle controls, and several other features. It also includes a datalogger that is way better than any other 2G datalogger. The feedback from the datalogger and the extra abilities of the DSMlink just make it easier to tune due to increased control over the car's operation. With the AFC you're limited to whatever tune turns out to be the best medium between multiple variables. It is easier to make power on DSMlink, and it's well worth the extra $300 over the AFC. If you take into consideration the cost of a pocketlogger, then it's really only $150 more. The benefits are definitely worth it. Either one can be purchased and brought to me. You don't need anything else to go with it. Also the AFC has to be wired in whereas the DSMlink is just a matter of unplugging your ECU and sending it out and then waiting to get it back and plugging it back in, then rolling straight to get tuned.