i believe stock is 14.5 and you can boost up to 16.5 anything else the turbo looses breath and won't make boost all the way to redline. I think this is correct. Im a nissan person.

 

Without any other mods, I would stick with stock boost levels but make them not drop with an aftermarket EBC.

 

The reason why you have to use caution when playing around with boost controllers on Subaru turbo cars is because the fueling won't be increased properly to match higher boost. While small changes might be okay (and I'm talking less than a pound of boost) anything more may run the engine lean with disastrous results. Without an aftermarket exhaust gas temperature (EGT) gauge properly installed, you'd wouldn't be aware of the lean condition until it was too late.

Engine management such as a reflash or piggyback will take care of both additional boost, fueling, and ignition map changes for more power.

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