To answer your question, no you dont need a tune for a muffler delete.
If you swap any part that impacts the intake or exhaust flow then you should tune. That means J pipe, intakes and some wider catbacks should be tuned for but if your leaving the midpipe stock you can skip the tune and enjoy your extra volume.
Keep in mind that these cars do not make any additional horsepower on any mods without a tune so any time you try to make more power you need to tune.
hope that clears things up.
Slow is Smooth > Smooth is Fast