In extreme cases, it can blow the muffler wide open.
Plugged muffler ot cat converter
Damage. Hole. Perished gasket. Incorrectly fitted. Corrosion.
You may if the noise level is too high. But that is the least of your worries. A defective muffler may cause your death or at the very least an accident. A muffler with a break or hole in it will allow carbon monoxide to enter the passenger compartment of your vehicle, especially if you are driving with the windows up. Carbon monoxide is odorless and tasteless gas that kills. This will cause you to feel sleepy and will eventually cause you to loose control of your vehicle. Get the muffler replaced ASAP.
It will eventually seize the pump up and may cause damage.
A clogged muffler can.
leaking or cracked manifold
I do not believe that your exhaust system should in any way cause your toque to become loose. Driving with your windows open would be far more likely to loosen your toque.
insurance
A hole in the muffler would cause a knocking sound in your muffler. A loose exhaust pipe can also cause a knocking noise.
no oil in engine or water in radiator will cause engine to seriously o/heat! and eventually seize! major engine damage!!
No. It will cause a problem with both back pressure and noise.