Bump Steer is a condition that occurs when your wheels have a toe change when they leave the pavement (such as hitting a bump). The rack and pinion's inner tie rods must travel up & down through the same arc as the lower control arm. If a rack and pinion has the inner tie rods that are spaced wider apart than the stock configuration excessive bump steer can and will occur.
There is an urban legend of sorts concerning what bump-steer is. Some guys believe that bump steer is the vibration or shaking that you feel when you drive. This is incorrect.
The easiest way to verify if a rack and pinion kit will or will not create Bump Steer is to measure the inner tie-rod sockets on a rack and pinion kit to that of the inner tie rods on the factory center link.
We spend a great deal of time and effort designing and manufacturing our rack and pinion kits to assure that work with the factory front-end parts. It would be much easier and cheaper for us to simply use an off-the-shelf gear and shorten it.