Finally got around to mounting the speakers - very happy with the result.
After a bit of experimenting I ended up stuffing the enclosures almost ending up with a closed enclosure (or to be more specific, similar to putting a foam plug in a ported loudspeaker). This gave the best and cleanest bass, although sacrificed a little bit of the deepest frequencies.
The sound is now powerful and clean with plenty of bass, working extremely well on rock tunes, but also good for general pop/rnb/dance music.
Also wanted to note that I've actually turned down both treble and bass to negative settings to help the midrange appear. I think I'm running treble at -2 and bass at -3 (helps the main speakers focus on other things but bass, and I can control the basslevel freely from the external amplifier by adjusting gain on the subchannel). I find this works very well.
After these adjustments combined with the new amplifier and SWS-speakers the total sound experience is now far superior to the original hifi sound system.
Just thought I'd share it to give people some alternative ideas. A few pics of the enclosures:
(note that the hole for the original cable socket was stuffed extremely tight with foam after mounting the speaker to ensure that air don't go through there, but mainly escapes through the original port)
