Direct from Hondata's website. They even state themselves that it is NOT a standalone system.
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What does Hondata do?
Hondata
modifies standard Honda engine computers (ECUs), adding features and expanding the capabilities of the ECU (e.g. for forced induction). Several products are offered, including tunable systems, tuning software and datalogging software.
Does Hondata cover my vehicle?
Hondata covers most vehicles from 1992 up, but some vehicles require the use of an adapter harness and/or OBDI ECU swap.
Use the application wizard to see what products are available for your vehicle, or view applications by ECU, applications by engine or applications by vehicle
Why should I buy a Hondata system instead of a replacement standalone computer?
Nothing runs a Honda engine as well as Honda ECU. End of story."
Quote from Hondatech debate of AEM VS Hondata
"you can ask for the long list of features that the AEM EMS provides over Hondata, most of which do not appeal to the average honda turbo user, like traction control (not 100% functional yet) and antilag, integrated boost control with closed loop feedback, ability to fire multiple sets of injectors, control outputs for things like methanol and nitrous injection (both switched output and PWM "analog" style), separate nitrous fuel mapping for dry setups, multiple o2 sensors, EGT fuel trim per cylinder, fuel trim in general per cylinder, auto tranny convertor lockup, integrated datalogging (without laptop), direct fire ignition control (1 coil per cylinder), knock retard (just like J&S) which can add fuel as well as retard timing, integrated 2step rev limiter. "
Debate 1