I appreciate you are convinced otherwise but I suspect that the words "competition" may just be a descriptive phrase to indicate that the owner has specified adjustable dampers.
The original design used a non-adjustable Bilstein, then came the Quantum units which were fully adjustable but expensive (perhaps it is these?), and finally adjustable Spax dampers.
The other possibility is the ride height setting, perhaps it has been set at the lowest level to minimise rear roll?
Again I am not an expert but to the best of my knowledge all the SSL: 5L systems are the same design. You can of course tweak the spring rates, the ride heights , and the damper settings to your heart's content, so perhaps the owner specified that he wanted it set up for competition.
