I wouldn't say NOS is a low boost setup.. Once u got a lot of oxygen in d engine, ur ECU will detect it tru oxygen sensor in ur exhaust & it will maximise fuel injected in ur engine..Yes, NOS is chemical forced induction, also nicknamed turbo in a bottle.
Btw about using the forged internals, wouldn't it depend an how much power boost you're putting into the engine? If relatively low (maybe say 30% power increase or so), then can still use stock internals, no? CMIIW though coz I'm very newbie on forced induction.
As for the legality, if say you install such bolt-on kit (turbo/SC/NOS) then afterwards you want to sell-off the car, would it pass puspakom inspection? Or you need to demod it first?
Usually NA use a wet system meaning the NOS system itself has another set of fuel injector to support a surge of oxygen inside d engine to make sure d engine won't have a lean AFR
Furthermore, usually NA engine has a high compression ratio thus making it unsuitable for NOS
I can talk about this all night long.. But i got to sleep too
Long story short, if u r thinking of getting a NOS.. Forged internals n turbocharged ur engine 1st
Don't repeat other people mistake.. Search d net.. Lots of information out there
Gudluck