Hi Joseph. I'm definitely NOT a guru of sensor/ECU mods, but I will input on what I know or believe.
I have read repeatedly where George Wiseman of Eagle Research, who developed the first EFIE's- has advised that an EFIE is to help retain or improve mileage gains, to be found from another engine mod for economy. Mods like HHO, the Groove, etc. He advises not to use an EFIE alone, but rather as a complimentary device TO a fuel-saving mod. Kinda like the Groove is the Steak, the EFIE is the Steak sauce. An EFIE without the fuel saving mod done first runs risk of going too lean.
Ron endorses Mike Kerhli of Fuel-saver.org, as the source for the best EFIE's. The info on this is in the fuel saver tab at right top of the front page here. IF your Honda has a MAP sensor, then Mike Kerhli has a device for that- and we have the Mapster still I believe.
4WheelBill is a solid tech- If I had a car just like his I would consider outright copying him!
and for some really good info about modding sensors and tuning w/ a computer- Karl411 posted the great article by Mike Hollar that was originally at Fuel-Saver.org. I just re-posted the article as a direct link to the original to give the original graphics on wiring schematics there, and it wil live in Tools of the Trade section of the Index, our "back room".
So, I humbly say- Groove first, document results, then consider the "steak sauce"!
Tracy G