to undercoat or not to undercoat???

Another vote for NOT undercoating. I have seen where cars rusted under the undercoating and owners never new it until it was too late. I would look at something like POR15. Think of this. How much does all that undercoating WEIGH? It's pretty heavy. POR15 is much lighter and will do the same thing. Lighter = faster and better mileage. I am in the process of scraping it off my car right now. I wouldn't spray that crap on a car if my life depended on it.