[DanEC]

I used LizardSkin on the underside of the aluminum floor and transmission panels and B-Quiet dampner (similar to Dynamat but much cheaper) on the inside covered with a blanket of EZ Cool double aluminum faced insulation. I don't think B-Quiet and Dynamat type products actually offer a lot of insulation value - there main purpose seems to be to dampen vibration and tinniness to make everything quieter and more solid. I used a 40 mil version of B-Quiet so as to not add quite as much weight. It's pretty heavy material. The EZ Cool is feather light compared to the mastic pads. The LizardSkin ceramic coating and EZ Cool are the real insulation items.

The aluminum skin/closed foam insulation ERA recommends for use that can be picked up at Home Depot (can't recall the name) works very well too and is inexpensive. I used some to extend the ERA insulation around the foot boxes, to cover the undersides of the boxes due to the undercar exhaust.

B-Cool was the least expensive material of it's type I could find that was not an asphalt based product.