After taking my 2007 Caliber in for it's first service the car was very very loud. Stepping on the gas resulted in a "no muffler" like level of noise. When the engine was not under load it is fine. The dealer replaced something in the exhaust system but that did not help. Now the dealer tells me they don't know what it is and they say everything is as it should be.

Anybody got any ideas as to what could becausing this loud resonance noise when accelerating??

 

That's very odd. I'd take it back.