[TerryH]

Most high compression heads do not add 20 hp; using Snyders 5.5 or 6.0 will probably net you around 10 more hp. As for extra wear and tear on the engine, yes if you drive hard and push it all the time, and aren't careful with timing and spark advance, you can do some damage. Many, many of our local club members have them, and they are probably the single most effective way to give your A a significant power boost without compromising the car. I have a Town Sedan, which is one of the heavier Model A's, and it certainly helped.
Terry