I found a company that makes adapters to help fit small-medium magnet speakers in the front. I can't recall the website but I found purchasing information on http://www.imprezawrxsti.com The kit also includes other things to help the install such OEM location tweater mounting bracket.

You'll be really hard pressed finding speakers that fit the front. It was a very-very tight fit on my '04 STi using mid-range Bostons (Rally Series) even with spacers.