I can't say enough good things about locking tuners. They are worth their weight in gold. While I wouldn't recommend installing them on a vintage Strat; for a new, out-of-the-box guitar they work wonders. They offer rock-solid tuning, and actually improve sustain by adding more mass to the headstock. If you're going with stock tuners, make sure all screws are snug but not too tight. If it still feels sloppy or will not hold the pitch, replace them.