Timing makes exhaust loud?

Ight, my mom got the timing belt changed. Then after, I started noticing the exhaust got louder. Is this possible? What if the timing belt isnt right tension and it changed the cam timing, could it alter the exhaust noise?

i can't answer you with all certainty, but I would assume, if the exhaust valves were opening sooner, at all, you will get a little more volume.