MetroMPG appeared to have success with a ~3 MPG gain when he lowered his Firefly:
http://ecomodder.com/forum/showthrea...s-35164-5.html
But no promises. You've a completely different car.
If saving $$ is your goal, you will probably have to own it a loooong time in order to offset the cost of lowering it. Especially if someone else does the install, and if you go for an alignment after.