Two things to be aware of. One, if you remove the spray head from the flex hose be sure and secure the hose because it is weighted and will fall through and out of the faucet body.
Two, the white plastic piece does do some restriction of water flow but it also acts as a back flow valve. The valve action keeps the water from dropping back into the hose. What importance this is I haven't concluded yet. The flow restrictor I understand but I don't understand the reason to stop the water from flowing back into the hose unless it's to lessen some of the water weight at the lowest connection point of that particular line. Or perhaps it's to keep the spray wet and not full of air.
Water will seek its own level so the flex line will have water it in regardless of whether the check valve is installed or not. It this case I'm not smater than a fifth grader or even an engineer.
2013 Voltage 3800, 2012 Chevy 3500 HD
2010 Yamaha V Star 950
2009 Yamaha Raider
Volunteering with Habitat for Humanity Caravanners