Timing Chain replaced and now car is louder than it was before

I have a 2005 Honda Accord LX, 4 cylinder, manual transmission, 155K
miles.  I just had the timing chain replaced and the timing adjusted.   When
I got it back the engine sounds louder than it did before especially in 2nd
and 3rd.  It now sounds like a sportscar instead of a sedan.  It almost
sounds like a sporty exhaust system is now on the car.   The mechanic
doesn’t seem to hear it because he does not know what it sounded like
before, but both my wife and son have made the same observation,
unprompted by me.   The mechanic claims that he did nothing to the
exhaust and he didn’t do anything that would affect the to make it sound
like that and says  that he can’t do anything about it.  It sounds strange to
me also because how could the timing chain have anything to do with how
loud the car sounds?  Can anybody help me (and my mechanic) to
determine what could have happened during the timing chain replacement
that could make the car sound loud now?  Thank you.