White is the fastest colour, especially for turbos..
On my own S2's I have always changed the chain and pads as soon as I buy a car (among other bits such as belts, waterpump etc) but also pay attention to the camshaft sprockets, they have a habit of loosing teeth if the chain is on there too long.
I check my chains and slipper pads on my s2's every belt change. But then again I change my front engine oil seals, tensioners, rollers, waterpump, thermostat and head gasket as well every second belt change, which for me is every 8 years for the whole lot and a belt change 4 years later. The head gasket is just because after 10 years they look like they have been used for target practice with a shotgun. But I don't do many miles in any of mine, but then again I doubt many people are doing the expected 10k to 12k miles a year in theirs, but if they are, they should use a schedule of 40,000 to 48,000 miles for the belts (as well as taking a peek at the chain and slippers) and 80,000 to 96,000 miles for the whole lot to be replaced.
But that is easy for me to say and relatively expensive if you are using a specialist. But not as expensive as repairing the damage that any of this failing can cost.