I did not use any foam. I just rubber all of the old glue off the headliner backing-it is a crumbly mess but basically will just rub off with a dry rag. I remember looking up and finding a video on youtube for removal of the headliner. I was able to lower and fully recline my passenger seat and slightly bend the headliner foam to get it out the right front door. I am also in So Cal and this burlap is so incredibly durable I do not think I will ever have a problem with it ever again in the car's lifetime.