Carb number?!?

hey wassup i've been wonding because i got friend who say they would buy a turbo kit then some say they'd build their own . well if i'm building my own like the manifold,turbo,downpipe,piping,intercooler, blah blah balah does it have to have a carb number so thats its "legal" so that i can get my IM or not?because when i check out then mani's in the mags and stuf. i don't see any Carb number or anything. so i'm kinda wondering :confused: