hi,i dont have a cat but was just wondering are you getting full lock on your steering?also have you set your camber link locations by the setup sheets? ill try to give you a rough guide to checking diffs (very difficult to explain without showing in person) hold the spur(be carefull the slipper doesnt slip)and one of the front wheels.then hold the other and try to turn it.it should be difficult to turn(hard to describe really how much resistence there should be) there should be some slip but it should require a fair amount of pressure.hope this helps (probably not
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p.s dont think stagger ribs will help they are more for when you are trying to tame down steering