Quieter diesel clatter?

[strictly_perv]

I love the on boost sound revving over 5k from the open filter and straight through to a tiny tiny back box
It's just the idle that sounds clattery, more than most 306's due to the lack of sound deadening

Thinking of putting something like this in plat of the original bonnet under lay

http://www.ebay.co.uk/itm/sound-proofin ... 1621wt_698