I replaced our existing 2.5 GPM showerhead with this one. My wife wasn't excited about it as she liked the high flow rate of that shower.  Since we live in Southern California and I pay the water bill, I changed it anyway.  I was expecting to take a hit on the performance side, but was pleasantly surprised with the amount of water flow and feel of volume.  Whatever technology Waterpik used to design this was pretty spot on.  There is a lag as you turn on the shower where the water fills whatever channels are used to generate the overall feeling of a higher volume shower head, but once it is going Several seconds, it works great.  At almost 3/4 gallon less per minute than our old shower head, I am quite pleased with value and performance.  I would buy this again if I had to do it over.