Agree 100% with Marklovski. I run the same Helium wheels and they are very close to the Proline 110b wheels you are looking at. A 15x6.5 wheel with around a 36-40mm offset is (in my opinion) a perfect wheel for the Mirage.
When you buy the proper size/offset wheel (which you are doing), wheel spacers aren't needed. Those Proline wheels will already sit out about 1.25 inches more than the stock wheels do. You will like that setup...and your car will look completely different. :cool: Check out my wheel/tire thread
here if you haven't already seen it.
The only thing you're giving up is some fuel efficiency. The wheel/tire combination you are looking at is heavier than stock and the tires aren't low rolling resistance. That may cost you a few mpg.