Several speed shops that modify Arctic Cat EFI models have started using a small â€œblack boxâ€ available from Advanced Performance in South Haven, Michigan. This small electronic device can add fuel to the EFI mapping, presumably by increasing the duration of the injector timing. It can not, however, remove fuel from the stock mapping.
To overcome this condition, a fuel pressure regulator can also be installed to lean the entire system, then you use the box to add fuel back where needed.
For example, Black Magic Racing offers pre-calibrated versions of this device that are tuned to work with many of their EFI performance packages. This allows fuel calibration of big bore kits and go-fast mods on EFI sleds that have previously been difficult to tune properly.
While not really intended for individual tuners, knowing this technology is available and has been successfully used by many performance shops gives you extra options when considering EFI modifications.