Replacing Saxo standard speakers, recommendations?

As above, i've replaced the standard headunit with a pretty decent alpine
headunit and now i'm looking to replace the speakers - starting with the
fronts. I have about £150 max to spend and think i'm gonna stick with
coaxials for ease of fitting. I just really wanna improve the mid/bass in
the front... surely anythings better than the standard speakers.

Thanx in advance.