It doesn't exist.
There used to be a bug with Vulcan Minigun that made you run faster with short barrel mod, but it's been patched long time ago. Like 5 years ago with update 83.
not sure what you mean with gun that increases speed, it could be the minigun glitch mentioned above, but you maybe mean the judge shotguns with HE rounds to lower your health and break your armor to get the yakuza boosts and second wind boosts
sliskiepalce is still here. QQ you did great runs some years ago - i watched them all, some time ago! and i was thinking on this minigun bug too that gives you 20% more speed (if i remember right) by equip 2 mods back then.
Hi Runner's there's been a little mistake with some of the RNG in the mod due to a misunderstanding of how the code works when writing the option for “No Power Down” for glitchless No Mercy, making it impossible RNG. Unknown Knight has informed us of this issue and fixed the option, but unfortun