Vauxhall Corsa load exhaust and engine sounds like a tractor

Over time the exhaust sounds like its getting louder and louder its got to the point where it's so load it sounds like a tractor. To add to this the car seems to backfire whenever in cruise, slowing down and going down in gears and when speeding up. I don't know if the leak is near the engine because the engine also sounds very noisy just behind it someone said it could be a manifold problem I'm not sure please help