Roll steer is kinda like bumpsteer. You just want it gone.
That said most setups will have at least a little. How it affects the performance of the car will vary from car to car and setup to setup. Some it won`t be very noticable,another car it may be more so even with the same amount. The bottom line is that if you get the LCAs level at ride height you`ll have minimized it a great deal. The easiest point to move is the rear lower mount and you can even use readily available bolt/weld on mounts to do it (of course we carry them,shameless plug!). The upper arms define (albeit very poorly) the rear roll center. Lowering the car too much (more than 1" or so) can put the RC higher than the CG which is a no no. The moment arms should form inverted pendulums both front and rear. The UCAs also provide almost all of the lateral axle location. Again they do it very poorly and even the best aftermarket arms need to strike a delicate balance between eliminating bind and providing good axle location. These issues will cause you a lot more grief than a small amount of roll steer caused by the LCA angle.
That`s were the watts comes in! It takes over the lateral axle location and RC location dutys from the UCAs leaving them with nothing to do but provide pinion angle control. Leaving rubber bushings in the upper axle mounts allows plenty of compliance to let the watts do it`s job smoothly and consistently. It also lets you tune the car by adjusting the rear RC height. Here`s a sneak peek of the prototype watts on a G body (shown at full droop) . Production G body bolt on watts are shipping now. Weld in Fab Fit watts are also available now (cut the crossmember to length,weld it in and the rest bolts in) and bolt in A body watts should be available by the end of July.
Mark SC&C