Well in answer to the original question I have just returned from Krazy Horse where they did a sound measurement on the car using a Testsafe sound meter approx 0.5m from the exhausts at 4000 - 4500rpm. The reading came out at 107Db.
Perhaps worth knowing for those side pipe trackday enthusiasts!
Going to krazyhorse on Tuesday morning for replacement heater switch so will ask them for a noise measurement .
