My Tundra was the test dummy for 74Welds billet aluminum upper control arms. I did research on different UCAs and camber, caster, cams, and tire placement. End result was 6* of caster depending on where you set the cams. Factory spec lets you run as low at 1.9 -3.4*. The low caster allows the tires to be thrown around by obstacles on the road. It makes the vehicle easier to steer is as it is more reactive but it is also more reactive to outside forces. Once at 6* the tires and steering wheel stay straight when you fit a pothole or other obstacle. I have not noticed any added resistance in the power steering or added effort to keep the vehicle going straight or turning. I have heard that the Camburg UCAs have close to 9* and people have noticed reduced responsiveness. I'm sure it is beneficial off road keeping the tires going straight but for on road it might be too much.