Originally Posted by tc3team
"With roll bars it enables you to run a softer sprung car without having the bodyroll effect of having it soft so you can create more grip through the shocks and carry more speed through the corners. But on bumpy tracks it can make the car unpredictable at speed".
As tc3team alluded, sway bars not only can make a huge difference in how a car handles - both positively and negatively - they are also one of those things that works for some folks and doesn't for others. And thus, me giving you my preferences will do you little good as drivers and driving styles vary so greatly.
I prefer to call them "sway bars" because when I think of rollbars those are part of the rollcage (or in place of) in full-sized 1:1 vehicles - but as the name suggests they are intended to contol how much a car sways (or rolls) through the corners. And thus, in realtiy, they are a fine-tuning aid used in setting up your car and their useage or choice can change from track to track and surface to surface.
To me they make a huge difference on how a car performs.
The big thing is that you're going to have to do some experimenting, as well as going onto the website of whichever manufacturer produced your car as they often have team driver set-up tips, to find just what works for you.
And finally, keep in mind - and though this may sound a bit odd - that front sway bars help control the rear of the car (via how rear traction is generated and when), and that rear sway bars control the front of the car (via how they react to steering input).
- hope this helps, and I'm sure others will chime in with additional info