You have to be careful of too much constriction, that will make the receiver want to squeeze right off the penis from the beginning and you will wind up removing more and more air until it will stroke properly again.
I believe the assembly guide tells you that you can take the constrictor and give it a slight twist before folding back that second layer over the housing. It is a cheap and easy way to try something “tighter”
I would really need to figure out who you are and look at your original or current measurements to give some tweaking advice.