What exactly does a front and/or rear stabilizer/sway bar do? Should I use either or leave them off? Not sure what to do, and how much of an impact they have.
A stabilizer bar helps keep the car from rolling in the corners, by transferring some of the weight from the outer tires to the inner tires, limiting chassis roll. The stiffer the bar, the less the car will roll in the corner. This comes with a trade-off, of course. The suspension won't soak up bumps and ruts as easily.
The use of an Anti-Roll (stabilizer) bar on the rear end will sometimes help with giving more steering, where the one on the front will give more traction in the rear.
If you have more questions about the functions of a stabilizer bar, head on over to www.rcdocuments.com and download the Associated setup guide for the B3. It's covered lightly in the book, but should answer all the questions you may have.