Got the car back yesterday and man is the sound better - I really can't believe how it is now compared to the standard installation. As far as I am concerned it was well worth the money. Only thing is you need to drop the treble down due to the tweeters in the door surrounds.
I am going to install some Alpine SPS-410 speakers in the parcel shelf on the weekend and they are a 4" speaker/tweeter combo.
Well if you are thinking of upgrading I would recommend the Alpine HiFi kit - glad I did it.