The main indicator of a problem with the exhaust is a change in tone and intensity of the exhaust noise when the car is running. If left without having it repaired parts of the exhaust system can fall off, which could be dangerous for other drivers on the road. The loud noise will also remain until you have it repaired.
Car Exhaust Replacement
Also, if you notice any of the following noises from the underside of your car then you should get it checked by AMS Tyres and Autoservices:
Rattling noises can indicate a loose bracket which are holding the exhaust system in place. Repairing noises could be a serious issue with the silencer and if you hear hissing or popping this is a sure sign the muffler or of the pipes is leaking or has corroded.
As with the MOT, emissions are very important, and your exhaust system could be letting you down! Do you have blue smoke? If so, this could indicate a fault from the engine with burnt oil. White smoke after starting could be due to internal coolant leaks or worse a leaking head gasket or a crack in the engine!