[Dragula]

Adding too much rear bar will cause the rear to break loose. It decreases body roll which decreases the weight transfer to the outside rear tire exiting a turn.

My Impala SS suspension has a stiffer front bar than stock, and the stiffest rear bar available. The rear bar was modified after the front bar, and it did increase the tendency to oversteer when installed. A freind of mine had the same setup and was autocrossing and road racing his Impala SS in the SCCA. He was actually ranked #1 in his class regionally in 2003(I think that was the year). When he got serious, he added a roll bar to the car which stiffened up the chassis. He had to downgrade the rear bar to the stock unit to decrease the oversteer condition that resulted.

The manufacturer builds in understeer because the average driver doesn't instictively know how to react to oversteer. I know we want to get our cars as neutral as possible. Adding a rear sway bar of appropriate design and torsional strength will decrease understeer. Too much rear bar in relation to the front will cause oversteer.

I have only heard this debated once before, and it was on this forum. I'm pretty confident that what I've stated is the truth. Buy a front/rear anti-roll bar set from a respected manufacturer, and you will probably have a well tested setup regardless.