Hey Rich, this was taken right off the Yosh site.
The NEW Yoshimura EMS (Electronic Management System) is an evolutionary on board device, designed to adjust fuel and (in most cases) ignition mapping. Yoshimura EMS units come pre-programmed with the optimum mapping for your bike. It comes in a high impact polymer case that plugs right into your OEM connectors. No splicing or modifications are required.
Features
• Profound tuneability allowing direct injector duration control and ignition timing adjustments (Ignition timing adjustments on selected models only).
Busa (00-02) have the ignition feature! Part numbers, 543-9025 & 543-9019.