actually stockers are 5x7.... if its the rear you could probably just leave the stock ones alone and just spend that money on better front speakers or a better amp....
as far as leaving the rears alone, i would really like that, but i do know that you boyz in the us may have different speakers in your 3's than we do in Canada. for example, I had an 06 mazda3 loaner the other day from the dealer. the speakers were much better than in my 05. the tweeters ae new for the 2006 year. a lot more bass in the stockers for sure. so, I dunno if your stock ones are the same as my crappy ones.
