The BR series coilovers use a large 46mm diameter piston in a 53mm diameter damper body to maximise oil capacity. As the damper unit opearates the oil contained within heats up. The viscosity of oil changes as its temperature varies which can lead to changes in the damping characteristics of the unit.
BC Racing only use a very high quality oil with their coilovers but go that extra mile to maximise performance and build their BR range with a large 53mm diameter damper body. This increases the capacity of the unit which increases the volume of oil contained which in turn reduces the peak temperature and so significantly improves damper performance.
This is the kit we recommend for the best balance of performance and comfort, designed by the factory to have the best overall compromise of spring rate, ride height range, top mount design and damping rate to suit the majority of car owners.
It is more than capable of dealing with fast road and track work but also retains a high degree ride civility so the car can still be used for mundane duties and long journeys without the ride becoming tiring.