The materials i used were sound insulation material and some good old crunched newspapers.
* Car in a mess!

* Through the 3 square/rectangular shaped holes, there was a large area of empty space, hence more air for resonation. I filled up this space with material and newspaper balls until the area was packed, but not too tightly.

* Finally sealed the 3 holes with the sound deadning material, put back on the quarter panels, and then again stuffed the empty gaps through the open sides as there was still space left between the quarterpanel wall and quaterpanel itself.

Took me around 2 hours? half that time was spent looking for tools, materials ( thanks to my brilliant idea of working on it at night time)..
And then to test it's effect, i turned the ignition on just to realise my battery was flat! coz i left the audio running! Clutch started it within the length of my driveway and took it out for a spin.
It made a huge amount of difference. Amazing difference actually. Didn't think a bit of junk material could do so much but it did! I highly recommend doing it (if you already havent done so) as the bass then actually travels smoothly and kicks stronger and it becomes more solid.
Next iam going to sound deaden my boot!