After porting, your boost will go UP. The engine has not gained any efficiency, but the blower is moving more air, therefore boost goes up.
Now if you add headers, ported heads, a cam, etc them you’ve improved the efficiency of the engine and boost will go down. That’s not a bad thing, the engine is now moving more air, which means more power.
Oh, and the rotor pack volume is 1.7L on the OEM blower. Porting improves the ability of the blower to fill the rotors, that’s all.
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2017 Chevy Camaro 2SS A8 Whipple 3.0, Mast Black Label heads, Fore triple in-tank pumps, 112mm TB, LPE +52% injectors, LPE BB HPFP, 15” conversion 1059 WHP/944 WTQ, 9.48@150