Dynamat and Expansion Foam

[Pancho]

Has anyone here used expansion foam in the rear wall of the cab and dynamatted the roof of their 2500HD CC? How difficult was it and do you have any recommendations?

[DenaliAJ]

I would stick with Dynamat and something like PolyFill or some other polyester cloth to fill any holes (like a pillow from walmart or a roll of polyester cloth).  It has been my experience that expanding foam is the DEVIL.  IT just keeps expanding, doesnt stop.  If you use it, use LESS than you think you need, or it will bite you.  Its a b*tch to get off if it runs somewhere you dont want it.

[LarryE]

don't use either  

 

dynamat falls off after time and foam is a no no

 

get some rockford fosgate noise killer spray, it gets hard and you will never be able to tell you put any on there (it doesn't expand)

 

I sprayed my entire cab in it when I was installing my stereo.

[MarkD]

LarryE,

 

Can you tell a noticeable difference?  Did you do any ambient noise measurements?

 

Thanks