stacked chips
The DP Tuner chip (or other Physical "chips") that piggyback on the PCM use the data from sensors and actually bypass the PCM's own internal fuel and timing maps to make the decisions on what to do with the data. Using ACTUAL sensor readings allows the CHIP to make "educated" changes to IPR and timing.
Stacking a "fueling box" with a chip usually causes severe overfueling, very high EGT, and SES lights due to "out of range" ICP readings/low HPOP.
You didn't ask about "tuners" (reflashing devices), but the effects of stacking a "fueling box" with a "tuner" usually results in the same fashion as stacking the chip/box.
You can't stack a "tuner" with a "chip". The chip will ALWAYS bypass the tuner's programming since the chip bypasses the EEPROM in the PCM.
In addition, unless there is programming present to compensate for transmission parameters (line pressure, timing, duty %, etc.), using a fueling box only will cause a slushy (and eventually burned up) auto transmission.
DP Tuner tunes are all you will need.


