JRT

Does anyone know what size door speakers will 'drop in'? Everyone seems to have a different opinion when I go into audio shops. I've got an Alpine head unit, and want a half decent sound without spending a fortune. Any ideas??

TR-S2K

Most 6.5" will fit the OEM speaker basket behind the door panel. If the magnet is too big to fit in the basket, you need to cut off the baskets but keep the ring, so that you can use the stock speaker mount holes rather than drill new ones. You also need XTC 6.5" speaker baffles, because the stock basket are there to protect speakers from water dripping down from the windows. you need to cut off the bottom 1/3 of the speaker baffles to vent just like the stock basket, and to connect speaker wires. This baffles should be installed between the stock rings and the door frames.

JRT

Nice one. Can you recommend any specific speakers that sound good without a sub / amp?

NFRs2000NYC

Whats the Budget.....its also going to be a little harder to get you a good deal, because most places I use are in the US, and you are in the UK.

TR-S2K

Each person likes difference sound, what I like may not suite you, you need to go to store to listen to some and buy what you like best that fit your budget. Many S owners prefer these speakers:
Adire, CDT, Crystal, Focal, Infinity, MB Quart and Boston Acoustics
Since you will power the new speakers with your HU's amp, which is not very powerfull, you should choose speakers with at least 90dB sensitivity, the higher the sensitivity the less power it will need to produce decent music level.
Example, speakers with 86 dB sensitivity will need 40WRMS to produce 102dB sound pressure level, but speakers with 92dB need only 10WRMS to produce the same 102dB sound pressure level.