As a matter of fact I'll find a quote about the differences between the sedan and coupes engine.
Hyundai had to redesign the intake manifold for the 3.8 Lambda RS engine to improve airflow and increase the engine noise that it makes when accelerating. The plastic intake for the sedan decreases the engine noise. The 3.8 engine in the Coupe has one of the best sounding stock V6 engines I've ever heard.
And another one
Will the aluminum intake off the coupe fit the 3.8 sedan?
I don't see why it shouldn't. The intake/exhaust and a slightly better tune are about the only difference between the sedan 3.8 and the coupe 3.8. So if you are looking for an easy upgrade - Get the coupe intake manifold and slap it on the sedan. 