Nightcore mod doesn't change the pitch, what it does is not correct the pitch like Doubletime does. And so it increases the pitch by 7 semitones (well actually slightly more, 702 cents... but it's well within human perfect pitch of raising it to the 5th), because that's naturally what a speed increase of 50% does (this is one great things about it... adjustments for pitch can add distortions, which can be annoying on some songs when they're DTd). Real Nightcore songs tend to raise things much less... a few semitones. Add in a lot of female seiyuu character voice songs, and things can get to chipmunk level without being chipmunk level (the Chipmunks were a full octave faster... aka, actually double speed). So it's not a bad idea to add pitch changing to Nightcore, although it does get into the area of adding settings for things that aren't really needed... because if Nightcore is too high, you can always just fall back to using Doubletime.