Shave it, it'll look handicapped if you won't, it'll get super long and not be very dark or thick, so you'll end up looking like you glued cotton candy to your face. The more you shave the coarser the hair grows in which in turn = manlier mustache. If you're going to grow a mustache, get a manly one or done get one at all. Don't be a disgrace to the mustache gods like;
Mario
Luigi
Princess Peach
Sirrus nevermind his mustache is handicapped too.
That one guy in the movie.