I have a Jabsco 1 litre accumulator tank on my fresh water system and have good steady pressure, and no pulsation at all. Install is easy, if you have 1/2" water hose. You just have to find a good spot on the high pressure side of the pump and cut the hose. The two cut ends go on the hose barbs and the third point of the "T" is the tank itself.
Defender looks to have the best price on it too, but you should shop around first.
Here is a pic of the Jabsco 1quart, 1 litre, and 2 gallon accumulators