[bobcowan]

Generally speaking, a sway bar is used to fine tune the suspension for varying or changing conditions. Especially important for race cars and heavy street cars with solid axles.

On a light car with IRS, you probably do not need a sway bar at all.

The bar ties the two sides of the car together, and uses the weight on one side to increase "weight" on the other side as the car is turning. The bigger the bar, the less independent the suspension becomes.

On my MII, I found that the rear bar worked well on the track. But disconnecting the bar on the street gave a better ride, and better control on rough surfaces. I used front and rear bars only on the track, and disconnected them on the street.

My advice for a street only is to skip the rear bar until you start driving it. And then you can make adjustments as needed.