i have a 2001 X and i upgraded to a pioneer head unit and pioneer speakers all around but what you have to do is match the output of the in dash head unit with the output of the speakers not just go with a large wattage speaker when the unit only outputs 20 watts per channel but in general to get better allaround sound go with a three way speaker that has alarge speaker for bass a mid for the middle range a a tweeter for the high end good luck
Greg