Though inspired by the notorious Prohibition-era gangster who helped popularize the term “G-Man,” Booth newcomer Machine Gun Kelly's stage name has less to do with literal firearms than with the Cleveland native's knack for lightning-fast flows. On newly-released promo single Leave Me Alone, leaked back in October '09 but presented here in its finished form, the up-and-comer reminds us that technically dazzling rhymes and emotional resonance are in no way mutually exclusive. Backed by a reflective, acoustic guitar-synth instrumental by Booth-acclaimed duo Rock City (who also contribute a memorable hook), Kelly vents his frustrations regarding haters, self-doubt and, of course, the relentless grind, building momentum from his conversational opening bars to a double-time grand finale. The rapper ends the record with a promise to keep it one-hundred and not start “[living] like Miley Cyrus.” If he can hold to that, it's a good bet the 19-year-old emcee has a bright future ahead of him. Digging this promo track? Keep it locked to the Booth for more from the promising up-and-comer.