YOU CAN REMOVE MOST RESTICTORS BY UNSCREWING THE SHOWER HEAD, REMOVE THE COPPER DISK THEN REINSTALL THE HEAD. REST EASY THE LAST I HEARD BIG BROTHER WASN’T CHECKING YOUR SHOWER !!!!!!!
I have a low-flow shower head and find the pressure quite good. Perhaps the holes are just plugged. Remove the head and inpect for clogging with debris or scale. If there is scale, you can soak the unit in Lime Away, CRL or some other product for removing water deposits. White vinegar may even do the trick. This should restore pressure.
The idea of the restrictor is to conserve water. Most units are designed to run with the restrictor in it. Still think you will find its illeagle to remove it.