Just a little heads up...
I was asked about this unit and after reading what it does i have to laugh a little.
Item Site
The HKS AFR is a fuel-adjustment device that regulates the air/fuel ratio by changing the airflow voltage output to the vehicles factory computer. The AFR was designed for vehicles that are lightly tuned (intake, exhaust system, etc.) and need only slight fuel adjustment. The 12 setting adjustment indicator allows the user to enrich or lean the stock fuel settings by approximately 1.0 A/R point in either direction (richer or leaner).
Now looking at that...you may think "Wtf Johnny whats wrong with it, if i can tune my afr down with this isnt it awsomezor!!?"
This is just like the S-AFC and will lead to the same issue of ******* with your timing and leading to a dead motor.
Remeber people removing fuel means the airflow reading to the ecu is less then the true airflow actually going through the afm thus the ecu thinks its under less of a load and begins to advance timin- boom omfg ringland!!