This is what I've gathered from months of reading...

Boost wise? with >good fuel delivery (and intercooler of course)< I've seen posts saying you reach 15 psi (max you'd wanna go on pump gas) with stock compression (talking about s14's 9.5:1 iirc).

Nitrous wise? with a >good direct port system<, I've heard people running a 100 shot on stock everything (don't ask how long it lasts).

Don't flame me if I'm off, just recalling posts I've read to the best of my ability.