> at much faster speed As others have pointed out, the speeds for Voyager 1 were because of gravity assist of Jupiter and Saturn while Voyager 2 was a gravity

> at much faster speed As others have pointed out, the speeds for Voyager 1 were because of gravity assist of Jupiter and Saturn while Voyager 2 was a gravity assist of Jupiter, Saturn, Uranus and Neptune. Jupiter & Saturn line up relatively often enough so we could try to outdo Voyager 1 speeds a bit with a lighter air craft due to various advancements. But it's unclear we'd learn anything really new from having sensors that reached further out and our technology for propulsion really hasn't meaningfully advanced to outdo gravity assists from Jupiter + Saturn. There's some proposals to use nuclear explosions behind a probe to achieve speeds of ~10k km/s which would be substantially faster but there's numerous obstacles (cost + international treaties banning the use of nuclear in space).