to really see any benefit on uprated speakers, they need a decent enclosure, the OE positions are gash and dont encourage good sound at all, whereas if you get hold of some door pods (or make your own), you will see an undescribable difference.
front speakers work best in a sealed enclosure, not the infinite baffle/free air rubbish that manufacturers set them up in. even using standard speakers, i bet my life on it, the best sound change you will make is putting the speakers in a decent enclousre, then go about replacing them.