I had a game where a Parnell player was moving as fast as a Goliath from one side of the map to the other side. When I asked him how, he said he had jetpack recharge and movement speed buff. It still seemed suspicious to me because I take jetpack recharge regularly as a trapper and I was never that fast though without a movement speed buff. This guy literally was right behind me shooting as he was moving and keeping up with my jumps across the map. There was no sunny.
I know there are some jetpack hacks out there for PC.