i dont know much about body mods, but i sugest you listen to a few different views as there always is...some people like to talk out of their ass and just spin shit just to sound like they know a lot, whereas some people actually know stuff!...do your reseach and save the heartache of doing things straight away.
police tend to pick on skylines that are noticably moded, and with P's, you're probably asking for trouble:(...but as dox said, it is your choice, and dont drive in a way that increases atraction
a mod that i would insist on(not loks either sorry)would be a 3" exhaust from the turbo...a cat back is good, but the bigger dump pipe does wonders for a skyline:D