When I ordered my MCS
in June 07, it had the Chili Pack with 17" wheels. I did not order SS as I thought it would make the suspension too hard in conjunction with the run flat tyres.
Initially I found the rear suspension tended to roll, so was considering changing the rear roll bars to the SS version. The cars now done 2.5K miles and there is no roll.
I presume this is due to the suspension 'bedding in', and I am very satisfied with the ride.
From what I understand SS increases the thickness of the rear roll bars fractionally, and that is the only difference.
suspension is by nature hard as it's a Sport Model. If you were going to use the MCS
in motor competitions then SS might be advantageous, otherwise don't bother.