All other EFIEs are old technology and assume a slow input waveform from the oxygen sensors. They produce satisfactory results when given the anticipated signal which is in vehicles up to model year 2000.
Cars newer than year 2000 are equipped with much faster sensors and make these “old” digital EFIEs ineffective.
If your vehicle is less than 16 years old, you require a Better Fuel EFIE that is able to manipulate fast input signals and achieve fuel economy gains.
The Oxygen sensors are the heart of the fuelling system and when you cannot control them, you have no gains.