Slipper clutch yes, Quickshifter no.
The slipper clutch works like any normal clutch but it limits the effects of rear wheel lockup/judder from engine braking when changing down.
Quickshifters can be bought, various brands available like HM, Translogic, Healtech etc. With these you just pin the throttle and shift up without the clutch. They are set to either momentarily cut the ignition to take the load off the engine.
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