Sound proofing / deadening

[Kevin H]

I'm looking to improve the soundproofing of the petrol tank on my 411. I currently do not have any insulation between the bulkhead and the rear seat in my 411 and I can clearly hear fuel sloshing around in the tank.

While some insulation would surely improve this I was thinking about doing some additional sound proofing / deadening on the tank.

I have looked at aftermarket sound deadening sheet, which appears to be a thin sheet of metal (probably aluminium) sandwiched between two layers of bitumen. This is stuck to any panels which transmit sound, but considering what it is, it's very expensive.

The theory I believe, is to add mass to the panel so that it takes a greater level of sound energy to make the panel vibrate, which is how it transmits the sound.

I was thinking it might be more effective and more economical to simply stick pieces of lead flashing to the panel, such as the walls of the petrol tank.

Has anyone tried anything like this or other 'home made' alternative methods of sound deadening?