In my session today I tried to contract my sphincter muscles for as long as I could at a medium pressure. It was around a minute or so.
Doing this with a rolled up towel under my hips gave the tip of my penis a vibrating sensation along with some involuntary contractions. This was definitely the most pleasure I’ve gotten about of the syn so far. However the involuntary contractions would go away when I would stop contracting.
However I’m worried that A: I may be contracting for too long? Could I hurt/damage anything? and B: the good feeling was almost entirely in the tip of the penis. Didn’t notice too much pleasure coming from the prostate.