To help maintain the life of the turbo, always allow the oil to come up to normal operating temperature before driving the car hard, when oil is hotter it's thinner and will flow around the engine and support and cool your turbo bearings more effectively.
Before switching the engine off, allow it to idle for about 20 - 30 seconds, this gives the turbo time to slow down, if you switch the engine off straight from a fast drive, the turbo will be spinning very quickly and the oil supply (which comes from the oil pump driven by the running engine) is cut off and the turbo will be spinning with no lubrication and won't last very long.
1 more thing, a Turbo for an RX8 is probably around £1300 so look after it