In my MK1:
Bought and fitted a Kenwood KDC4031 head unit.

And was left with the usual

'crap speaker' problem, was just gonna go and buy and try to fit some 6x9s when i remembered i had, in the loft, some TECHNICS supplementary speakers from my older home cinema.

They sound superb coupled with my standard front speakers!! I have managed to securely attach them to the centre column, at the top, one either side

(in between the head rests) I have wired them as rear speakers, with the wiring going from the head unit straight under the arm rest centre console and up behind the centre storage box.

Give it a go if you are looking for a cheap and easy install.

They are 100w each 8ohms and sound great the head unit powers 4 x 50w.

Just thought i'd share that one with you all!!!