I though I would share my experience with the XO-1 and the TQi Radio. I noticed the steering control on the TQi radio felt a bit heavy and the car had a tendency to pull to the left or right. The steering problem was not consistent and the wheel would center with no input from time to time. I looked at the steering linkage and servo on the car, no problem there. Next I inspected the TQi Radio, here is what I found:
The foam grip on the steering control was too close to the body of the controller, this caused the steering to stick slightly forcing the car to pull to the side.
I moved the foam away from the body of the controller allowing the steering control to move freely.
I don't know if this is the same issue others are having with their XO-1 pulling, but it is worth a check.
Hope this helps