Sound deadening materials

[lansdownplace]

Hello all. I was considering what I could do to enhance my 412 and making it a bit quieter inside would be a real plus. It has standard carpet underlay, no bulkhead insulation and intriguingly closing the air vents has a tremendous positive effect on improving a sense of solitude when driving

What recommendations would you make to address this? I have had a look at few options on the internet, but as to whether they are effective or not, I have no idea

regards

Paul