I read that on fitting the main belt it has 150% of the strength required and at end of the belt change duration/mileage/cycles it is still at circa 100%. One Coupe mechanic told me he has never seen the main belt go on it's own on the 20v turbo; it is as we know the aux belt/tensioners etc that usually take out the main. I have taken the main belt up to 8+ years and circa 40k+ miles (wouldn't recommend it though) but do the aux belts and tensioners every 3-4 years.
had a pulley manufactured with a guard I seem to remember.
Traffic light Grand Prix's and banging the car off the limiter are a no-no for the Coupe and it's belts IMO especially so if running big power increases.