From the Wikipedia article, List of artificial objects leaving the Solar System:
Although other probes were launched first, Voyager 1 was able to achieve a higher speed and has overtaken all others. Voyager 1 overtook Voyager 2 a few months after launch, on 19 December 1977. It overtook Pioneer 11 some time in the late 1980s, and then Pioneer 10—becoming the probe farthest from Earth—on February 17, 1998.
Voyager 2 is also moving faster than the probes launched before it, and thus overtook Pioneer 11 in 1997 and will overtake Pioneer 10 sometime in 2021.
New Horizons will also likely pass the Pioneer probes, but will need many years to do so. It will not overtake Pioneer 11 until ~2082 and will not overtake Pioneer 10 until ~2130. Barring some unforeseen gravity assist it will never overtake the Voyagers.
My query is why Voyager 1 is faster than everybody else? Even New Horizons would never be able to overtake it, even with its more modern technology.