I fail to see how a twisting force on the strut is going to cause a steering rack failure. This force would be on par with your steering input (and the equal/opposite force imparted back from the road through the tires), and should be a force that the steering rack is more than capable of dealing with.

I'd guess you're dealing with a range-of-motion issue on the inner tie-rod ends. The car is lowered to the point that the angle of the tie-rod end at the rack is somehow binding and putting a force on the rack that it was not designed to handle.

Solution: Raise the ride height up closer to stock, lower the steering rack, or modify the mounting point of the outer tie-rod end to reduce the angle at the inner end.