[tholyoak]

There are actually a few 'ROW' programs, but I assume the one you are interested in, is the one that doesn't use post cat sensors. This obviously only use pre-cat sensors to control the mixture, ignores the need to depress the clutch to start the car, doesn't use the air pump for cold starts. Also it is virtually impossible to get a CEL as the tolerances are much greater on the ROW program. Those are the differences off the top of my head.

In earlier Porsches, the engines were higher compression and used higher octane in europe and thus used a more aggressive map (timing) than the USA/Canada program. Therefore a performance advantage was gained. This is no longer true, at least on the Boxster.

-Todd