Hi Prizen, I really can’t see how you can I’m afraid, anything of any thickness on the back of your door is going to make the roll at the top much much wider, this will also affect the "gearing" effect on the motor, also I would imagine that a larger diameter roll at the top will no longer lineup with the line of the door so instead of the door material being pulled inwards towards the back of the garage the reverse will be the case and it will end up a right mess.
How about looking at the design of up and over garage doors that are made of panels hinged together and make one of those out of King span, it will be so light you won’t need a motor and you could just lower it down to fit against the inside of your roller door when you want to insulate the noise. Might even be possible to somehow attach it to the bottom of your roller door so that when that goes up and down the insulated panel one does the same inside? That might be a step too far ha ha Ian
Maybe I ought to patent that!
@Prizen when I bought my new garage door a couple of years ago I went for a rolling shutter door with remote control, it‘s not insulated as I had an up and over manual and this is far better In all aspects BUT why am I writing this is well there was an option to have an insulated version but I choose against it so it may be possible but you may have to speak to a professional.
If it's double skin with hollow centre then I guess you could drill a series of small holes in each slat and fill with spray foam filler but while it will have a dampening effect I don't know how efficient or cost effective that would be, if single skin type then I think your only options are probably replace the door of add a removable secondary panel of some sort.
Mine is insulated aluminium and the innards of each slat are just foam.