I used self adhesive insulation tared sheets,made for the job. They come in 400 x 400mm squares or there abouts. Then i placed another layer of adhesive sheets of aluminium engine bay insulation on top, all available on ebay, just type "engine bay insulation"in search. I also treated the side and front engine covers as well and it has worked great. A massive difference.
I used this http://www.screwfix.com/p/evo-stik-flashband-150mm-x-10m/55009;jsessionId=3q3qRMqRJJh2sflLztWNvQWZt3GxNNtJv1mckd89VJlypG84pJQh!-1229104950!1363962417736 which you might be able to find at work then a layer of this from Jules http://www.ratsport.com/PBSCProduct.asp?ItmID=10101849