On my previous boats I have normally run 34 on the shrouds from memory. How do you get the tension on? Is it the classic lightweight welsh method of having 2 eyes in the ends of your wire, a piece of dyneema, and then just pulling it on till the eyes meet? When you achieve that, then you have got the tension right!
Under normal, powered up circumstances, I would suggest that a LOT of tension is the way to go. Maybe ease it off a bit when it is really light. All the hulls and rigs are different, so there is no such thing as 'normal'.