Besides Jet, is there any other companies that upgrade/reprogram 5th gen ecu's? The ones I've seen like Skunk2 seem to be for every car but 5th gens. Also is there a benefit to an upgraded ecu even with a VAFC? I understand that the VAFC changes air/fuel ratios and the vtec point, but besides the rev limiter, what else would be changed with an ecu that a VAFC couldn't do?

 

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.