A softer front bar:
1. Increases front chassis roll.
2. Increases front grip or traction, while decreasing rear grip or traction.
3. Slower steering response.
4. Increases off-power steering at corner entry.
A stiffer front bar:
1. Decreases front chassis roll.
2. Decreases front grip or traction, while increasing rear grip or traction.
3. Faster steering response.
4. Decreases off-power steering at corner entry.
A softer rear bar:
1. Increases rear chassis roll
2. Increases rear grip or traction, while decreasing front grip or traction.
3. Less on-power steering.
A stiffer rear bar:
1. Decreases rear chassis roll.
2. Decreases rear traction, while increasing front grip or traction.
3. Faster steering response in high speed corners and chicanes.
4. Increases on-power steering.
PLEASE NOTE THAT BIGGER IS NOT ALWAYS STIFFER AND SMALLER IS NOT ALWAYS SOFTER!
A bigger front sway bar increases understeer
A smaller front sway bar decreases understeer
A bigger rear sway bar decreases understeer (more oversteer)
A smaller rear sway bar increases understeer (less oversteer).
Really, what you are doing is changing the rate that weight gets transferred to a tire. The stiffer the sway bar, the faster the weight gets transferred to that wheel, and the sooner it reaches its limit and loses traction.
That is why a bigger front bar gives understeer, even though you think the opposite would happen. Yes, the bigger front bar gives a better camber pattern, allowing the tire to have a more efficient contact patch (i.e. it is less likely to roll over onto the shoulder). But, if you are transferring the weight to the front tire faster than to the rear, that front tire is going to lose traction faster.