You can limp the stock Allison with an Edge. Been there, done that. You can read about how Allison's normally fail as they start to limp.
EGR delete isn't necessary until about 30 PSI of boost. Around there it starts blowing open, but prior to that, no performance issue since it shuts off at full throttle.
Just adding boost on a stock tune won't actually increase horsepower, since there won't be any extra fuel to burn with the extra air.
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