318 rebuild for turbocharging

I hear you T56, sounds like a nice 318 build btw. My understanding is that a compressor takes in air at a certain pressure and increases it by a set amount (boost pressure). If you increase the inlet pressure the turbo will just compress it 10 psi more whether it's 5 or 20 psi going in. I'm pretty sure it does work like that or else compound turbo/supercharging wouldn't work...?? Not trying to knock you btw just discussing :)