[Nglvayhp]

I don't think you are looking at "no more gaps" I think thats just an acrylic putty sort of stuff, I would go to either a car panel beating shop or a place that supplies them, they have sheets of sound deadener they stick to the inside of car doors. The expanding foam is expanda foam or similar names, the cheapest foam stuff can be bought at Bu*****s. Its very messy to use though, if you get it in the wrong spots it leaves a very sticky mess until its set, that includes your hands, wear disposable gloves.
As an afterthought I think supercheap auto have spray on deadener in cans.