OBD is the emissions generation of your car/engine. For Hondas, OBD0 was 88-91, and didn't have very much in the way of emissions stuff. OBD0 ECUs are pretty tuneable. OBD1 was 92-95, and are pretty tunable also. OBD2a is 96-98, and these ECUs aren't really able to be tuned because of some complicated stuff I won't bore you with, and OBD2b is the same deal, 99-00. All these generations have different standards for emissions, and switching between them can sometimes be a hassle, but that's usually because of differences with distributor signals and IAB (GSR) signals during the different years and differences between JDM and USDM ECUs..

Refresh my memory, what car is your Y8 in? Are you looking to do ECU tuning or just a plug and play engine install in a different generation car? I don't remember what your situation was.. You can email me or PM me, I'll answer all of your questions..