Was on my way to the airport at 545 this a.m. and got thinking about diesels and the term chip stacking and how they can get double the power from that sorta thing vs just one tuner.

Does it work like this? Please correct me if im wrong....

The plug and play tuner's will alter the signal from the truck PCM and essentially tells the engine on the back side that it needs to allow more turbo boost and more fuel at appropriate RPM to give a gain in output? Now when you "stack" them my theory tells me you hook the two tuners in series due to the plug and play ability of the connectors and the alterted signal coming out of the first tuner is understood as a regular PCM signal by the second box which the second one then further cranks boost and fuel etc...??

Do i have the general idea here or am i way off??