I spent the week in Warsaw and was in Institut few times. The Saturday was very good - a lot of people in different ages and a lot of action. I had some very hot group actions in the basement. On Tuesday naked party was ok as well. Other days there were just a few guys inside and in fact nothing happened. So my advice is go there on weekend, on weekdays choose rather other places, like sauna Fire which is just 5 minutes in walking distance. PS I haven't been in Institut on Friday because it was fetish Master&Slave party with obligatory dress code. And this is not my piece of cake.