If you increase the length at the bottom of the rod this would increase the lower gap, thus decreasing the front to rear Coupling. Gap on the top is, rear to front coupling. Gap on bottom is front to rear coupling. The gap on the bottom is almost more important because front to rear coupling is encountered more and directly relates to the riding characteristics of the proaction skid. I think the thoery here is that the skid comes to heavily coupled and by increasing the lower gap it uncouples the action. If you mess with the shock lengths, its a good rule of thumb to stay near the stock gap settings, which might require you in increase the lower end of the rod because you have removed all spacers and you are still not getting the proper lower gap.