You may get even more gains by doing a grille block. I picked up 1.4 MPG on my '00 Jimmy with that mod alone. Mine was on the outside, and VERY obvious (and pretty ugly, too).
I know you don't want it to look goofy, but they say you can still get gains by putting it BEHIND the grille & painting it black so it doesn't really show.
Be sure to carefully watch your engine temperature, though.... I blocked my grille so well it overheated & I had to cut a hole in it to let some air in. I eventually found a really good compromise, though - had to enlarge the hole once.
Bill