Hi, this just started yesterday, on start up all is fine but after driving for say 10 miles sounds like there is a crack in the exhaust, nearer the engine than the tailpipe and it pops and bangs on over run..it's a standard exhaust system, i've only had the car for a month and it's been perfect up to now. Could it be a small break in the exhaust that only manifests after its warmed up a bit?? very unusual in my experience. No loss of power or performance from the engine by the way but worries as don't want to do any more damage and cant get to a garage for about a week. Can you help??