I suspect that the hardware is the same, or very close. But, the S4 has a different throttle position sensor and different injectors than the air-cooled bikes, so it may be different HW from the other Monsters due to different resistance values of those parts. Likely the connectors are different too. I don't imagine the M800 and M1000 are all that different hardware wise, so I don't see a need for different part numbers, although maybe it just covers the maps that come on the CD/software.