A Piggy Back FMU is all fine and dandy if you can adjust your timing dwell past the limits of the OEM software...

Perhaps you don't understand the workings of the Bosch Motronic 2.8 ECU and all the associated sensors... Let me explain as quickly and simply as possible in real terms with hypothetical values.

Your NA ECU is designed to adjust fueling and timing from -10 to +10 based on your MAP values, 02 sensor values, Load Calculations, Throttle Position, Knock Sensor, etc. These are given parameters that are written into your ECU software.

The forced induction ECU is designed to adjust fueling and timing from -20 to +20 based on MAP values, 02 sensor values, Load Calculations, Throttle Position, etc. These are given parameters that are written into that ECU software.

If you introduce more AIR + FUEL into your engine, say +15, the ECU will only be able to adjust timing to +10, thus KAPUT on your potential HP gain and goodbye smooth running engine...

So, if you want to be a stubborn semi educated DIY Hot Rodder, by all means install a forced induction system and a piggyback fueling system... Let me know when you throw it all in the trash after you can't get your engine running properly because the timing is far too retarded...