Have seen a few threads that talk about replacing the headliner with marine carpet. Being a little taller than average havingno headliner (car doesn't have one anyway) would be an asset.

What is the go with marine carpet? Do you put some sort of soundproofing underneath it? Is it best to get someone to do it for you?

Any advice appreciated

If you're putting marine carpet in as a headlining, you may as well just bung it in 'cos it wont stick if you put a deadener on first and it will do the job of a deadener.