Factory tune won't allow left foot braking/heel, toe....also won't allow you to rev above 4 grand I believe... So to fix rev hang, and allow you to actually rev it you need a tune...
HOWEVER! you have zero reason to rev that high standing still... Especially if you are basically stock... Your car will only sound like a sewing machine... regardless of how high it revs sitting there you can't dump your clutch and burn... You also really can't get an idea of what the exhaust or intake sound like without the car under load...