The S&P rearsets for the S4 are prett simple in concept, and MUCH lighter than the stock parts.
The stock parts are 5.9lb for the peg assemblies PLUS the weight of the rear brake lever and gearshift lever (I don't have the weight of the pedal and lever), whereas the S&P rearsets are 2.2lb INCLUDING levers if solo, and add 2.2 lb more for passenger mounts and pegs.
The CycleCats offer WAY more adjustment range, but are heavier (still lighter than stock), but have much more complexity to them.
See my other recent postings on weight reduction and rearsets for more details.
Jim G