What are rack spacers and do they work?
Whichever method you use, their purpose is to extend the travel of the steering rack. They allow the rack to go further in to it's housing, resulting in more steering angle. In short, yes they work.
The question is how far can you go, our 4mm rack spacers have always been popular with many people admitting to running 2 rack spacers per side, I personally think that is a little to much so I have made a stock of 6mm thick spacers as a trial.