So I'm reworking a lot of Street Rats:
Combat is getting a huge overhaul, but that's just paving the way for some later changes.
First, armor and hardened armor are being replaced by a new Protection system; they still exist, but only as binary states (you are either armored/hardened armored or not armored/hardened armored).
Protection ratings are calculated as the two highest sources of Protection plus an augmentation, with the caveat being that no Protection source can be counted twice: cyborg/drone sources of armor count as augmentations.
So, for instance, a character could have Toughness-Armor-Augmentation, Armor-Armor, Toughness-Augmentation-Augmentation or so forth as sources of protection. Wearing two pieces of armor is significantly sub-optimal, however, as you can only wear one piece of armor with an Armor Penalty rating and wearing two pieces of armor imposes an additional Armor Penalty, which now reduces Defense and Speed to give a greater nerf to heavy armor users.
Hit locations go bye-bye, which means that some minor armor rebalances have been done: codifying armor's Storage statistically is a thing, and the new armor system paves the way for exotic armor, like active camouflage. This also allows a number of mechanics to be simplified, and removes a step of combat. It also gets rid of my players whining at me about the prevalence of hits to the left leg, which has been a source of both amusement and agitation for me.
Removing hit locations allows me to handle cyborgs and drones a little more simply and keep them as a coherent part of the combat system.
Finally, the automatic fire modes have been improved to make them less universally garbage, while aimed fire and rapid fire now increase AP (though aimed fire still increases damage to a lesser extent than it used to) to make them a little less assertive in the fire mode field.