EFI is readily adaptable to a coil/distributor ignition. With the XFI, the control box electronically handles the timing functions, so the distributor's advance mechanism must be locked out. MSD distributors come with instructions and the required pieces to lock out the advance mechanism, and this is a modification accomplished relatively easily on most distributors. The FAST XFI is compatible with OEM electronic ignition distributors from most manufacturers. A conventional distributor will allow batch-fire of the injectors. A sequential system follows the firing order with the injector pulse on a cylinderby-cylinder basis. To time a sequential system, a cam-position signal is required so that that the control unit has a reference of which cylinder is firing. A dual-sync distributor is needed for this cam reference signal. MSD and Mallory among others manufacture distributors with this feature, while FAST is tooling up for a full line of dual-sync distributors.