Stock HU turned all the way up to 31 and It sounds horribly distorted and not as loud as it should be....
I checked and there is no amp in the trunk for the components.

 

Bose? Non-Bose?

If it's bose, the amp is in the trunk. Sedans it's under the rear deck, coupes it's by the spare tire.

If it's non-bose, the amp is inside the headunit.

Regardless, failure of factory amps and headunits is so common in these cars it's ridiculous.