More boost = more backpressure.
You turbo is designed to operate within a specific "range", get out of that range and backpressure increases, and the air coming out of the turbo is beat up and way to hot.
Cooler, more dense air with low backpressure is what makes power.
As far as stacking tuners..........dont do it!
Buuuut......a chip will override a tuner anyways.
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