VAFC only changes fuel via the MAP sensor signal. if you're boosted, they VAFC will trigger the ECU's boost fuel cut.

a reprogrammed ecu will allow for 3D ignition timing in addition to proper VTEC crossover and fuel adjustments. it is also compatible with boost at the proper settings.

no one has the ability to hack the original 5th gen Prelude ECU. Jet says they can do it with an OBDII programmer, but all they can do is alter the ignition tables.