Thanks Bealaddison, will be interested to see what you find as a comparison.
Yeah was thinking about the length of screws etc and have some the same as what's used in the rear panel fixings. While it looks like a false floor arrangement under there I'll be marking the drill depth to make sure we don't go too far.
Hope the upgraded bags instal goes well and you get some extra wave out of the upgrade.
Cheers BruceR, Melb AUS.