Why not try soundproofing the inside rear of your car first.

It's an easy job to undertake, albeit one that i havn't got round to do myself yet .

All thats involved is a trip to Halfords for the soundproofing stuff, or maybe even some old carpet.

1/ Remove the carpet in the boot and cover all over, around the spare and under it in the wheel well.

2/ Lift the rear seat up, which i didn't even know it did until we went on a meet and Scotty showed me . And again, cover the floor pan.

As i said, i havn't tried it myself yet, but i recon it would work a treat, and at really minimal cost.

Put it this way, have you ever got into a Fiesta Encore and shut the door.....CLANK!

Get into an LX etc, and just a nice thud.

What did Ford do to resolve the tinny clank, one piece of self adhereing sound deadening on the inner doorskin.