What would randomly make an exhaust sound loud and raspy? On and off with the days

 

Have you check carefully for an exhaust leak?

 

multiple times. and if it is an exhaust leak it would always be loud and raspy

 

If the abnormal noise is produced by the exhaust system, I would think that there is an exhaust leak or excess vibration in the system that causes heat shield rattle or exhaust pipe or muffler bumping against the under-body.

Alternatively, the noise is coming from the engine.

 

well loud some days and not others MIGHT be the guts in the muffler are busted loose or rusty....

or posiblyyour donute gasket off the header is broken or cracked and the pipes flex just enough some times to leak and not all the time..

best way to find the leak is as soon as it happens being loud again then keep the motor running and jack the car up and put it on jack stands and crawl under to try and find where its loud at.
you should be able to hear a leak.... and s hould be able to see any rusted pipes that need replaced if that might be a issue...

wheres the loud raspy sounds coming from? if its coming out of the tailpipe then id say its the muffler going bad....

 

+1. I had this problem on my car. It would sometimes be loud and sometimes not. finally it came apart permanently and was only loud when I was accelerating.

When the car is cold, jack it up and wiggle the pipes, looking for excess play at the joints.