Bumpsteer kit would probably be a good improvement, but people often confuse bumpsteer with driving over bumps and car going all over the place. While bumpsteer kit can help that, it is mostly meant to keep the wheels pointing the same way on the track. When the car will lean one way, toe difference will increase due to different arc of the tie rod end, and you end up with understeer, aka wheels fighting against each other.
X2 Ball joints are a cheap band aid to improve the geometry of the front end when lowering the vehicle too much. The problem is that it only compensates for just over half inch of drop, which is essentially nothing. A better way to go about restoring front roll center, would be either not to drop the car that low, or get a K member that has altered control arm mounting points. Another thing is that altering the geometry closer to to the center of the vehicle is more effective than altering it at the spindle. I have a roll center calculator, and it has shown that camber angle and motion is better, if you compensate for one inch of drop at the k-member, than spindle.
