I've used the stuff twice now, 2 different cars, it works well. The really noticeable difference is long drives, very little heat in the floorboards. I use the same formula as Vince provided, (thanks Vince!) no problems after 2 years. I borrowed a undercoating sprayer from a friend, one gallon 2 coated everything I needed to spray on my coupe.
"When I was younger, I could remember anything, whether it had happened or not." - Mark Twain