All banjo are diffrent, just tweek it down till it sounds good but don't do it all in one day. When it gives a nice ring when you thump it you're there. If it stops ringing and starts to give a dull thump, you're past the sweetness, back up. People will talk about tuning the head to a note or wolftones if you tune it to a sympathetic note. (The note of a string) I've tried all that jazz but in over thirty years of playing the damn thing I always come back to the before described method. Remember this, you can mess up a good rim or flange with to much torque on your head. And as to the price of a torque wrench, how many beers can you buy with that cash.