Sorry for the late response!

It's loud enough for me, even at 80mph. But is it loud enough for you? Hard to say. I don't worry about sound quality all that much in a convertible, I just want to hear the programming I want to hear, when I want to hear it. There are plenty of times I just turn the thing off and listen to the Magnaflow exhaust as I run up and down the gears!! An iPod hookup was essential for me, however, and the St. Louis has the added benefit of the SD Card slot - nice bonus.