Pringles, are the only chips that are safe to stack. A wise man once said
To answer your question more in-depth. The term "stacking chips" comes from the dodge guys who can have boxes that do more than one thing. For example they could have a programmer that adds more fuel, but does not increase timing. Then they can add a timing module to achieve the desired result.
Our trucks only have about 2 safe ways to increase power, first and foremost is a chip or programmer. These completely override the stock computer program and makes the drivetrain operate according to the custom tuned chip / programmer.
The other mod that is popular with our trucks is an ICP
mod. This is a resistor placed in the wiring harness to the ICP
sensor. It reduces the value of the reading the ICP
sensor gives the PCM
and therefore the PCM
compensates by asking for more pressure. More pressure to the injectors = more fuel = more power.
Only use this if you DONT' have a chip though, and expect minimal gains.
When you get a chip or programmer, the tuner has already increased the commanded ICP
value and the ICP
mod would just complicate things.