insulation/roof

I'd like to have some suggestions for insulating the cowl & roof of a truck.
I am thinking that a product that could be sprayed or brushed on
would be the easiest.

I don't know if you follow the project33 web site but her is Scotts new post on how he insulated the coupe.
http://www.project33.com/article.cfm?ID=810
I went to the company web site and they also have a roll-on thermal barrier.
http://www.cascadeaudio.com/
I looks like a good product and as I understand it, cheaper than Dynomat.
MikeC

Thanks for the replies Guys. What I am looking for is a paintable insulation that I can get from home depot or lowes. I notice that they have a product called cool roof. Anyone stories on this or a similiar products that are not high buck?