Does it get quieter after the engine runs a few minutes?
Are you listening to it with the hood open now rather than from the drivers seat?
It's possible it is just the 'clutched' radiator fan that makes a roaring sound when the engine is first started, like they all do, and you are just more aware of it now while you are checking stuff out! (Possible)
Best thing, i think, is before doing anything else, take it back and have the installer check it out.