Dont bother with the L7 midrange to begin with - just the L7 tweeters makes a big difference - you can add the midrange later if you want to (saves £100 or so if you dont!)
the SWS-8 subs are 8 inch (boggo ones are 6.5" I think) - you have to modify the 2 enclosures under the seats slightly - have a search on here.
Cant comment on the Alpine amp, but the Blaupunkt is a good one!
One thing I didnt say - if you are going to change the subs to SWS-8, you have to drive them directly from the amp instead of using the stock cables, which share the front speaker inputs - but thats a simplish job of routing cables from the new amp in the boot to under the seats.
If you are planning to do it a bit at a time, do the tweeters, then the amp, then the subs, then the door midranges.
If you are going to go for SWS-8's, you can only usually get them from the US - I found some on a UK ebay site and bought them, but he actually had no stock - but they are currently held at customs............
http://shop.ebay.co.uk/?_from=R40&_t...313&_nkw=sws-8