I believe it's always better to tune the ECU itself to work with your particular engine setup than using a piggyback to "fool" the ECU.. You'll be doing the same thing as you would with a Hondata system, which is just commercial software instead of freeware. Hondata just protects their profits by making you use the little box or board, which is a copyright key (or "dongle" in computer speak)..

Certain really sophisticated ECUs like the 04+ WRX ECUs will actually compensate and change their tuning if you use a piggyback.