I've seen a number of threads discussing how stunbolt/stunball, Stick-n-Shock, etc. are too powerful and how armor converting damage to stun can actually make a character go down faster. This probably wouldn't be a complete fix by itself, but it makes stun attacks less of a sure bet without changing any rules.
Overstim
Duration: 10 x 1D6 minutes
Effect: Eliminates injury modifiers from Stun damage
Description: Also known as "hot stim", overstim is a bigger, badder version of the stimulant patch. Users completely ignore injury modifiers from Stun damage, and they won't fall unconscious when Stun damage reaches its maximum. Overstim can even be used to revive someone who's been knocked out due to Stun damage, but anyone revived in this fashion suffers from Disorientation.
While overstim is more powerful than any standard stim patch, it's also a much rougher ride. Users are often jittery and have difficulty focusing. Some also suffer from numbness or mild hallucinations. When the drug wears off, the user suffers 6 Stun damage (unresisted) as well as Nausea (treat as power 4, no resistance test). As with stimulant patches, anyone on overstim is unable to rest.
This game effect is already possible with an adrenaline pump or pain editor -- the drug version just makes it much more readily available. Would this be an effective and appropriate counter for stun attacks? Would it cause any balance problems of its own? Do the after-effects look about right?