I haven't nailed down a specific ratio for my trees yet, since I haven't gotten a large enough production.

But yea, 40:! is a general rule. Some types of maple trees produce a noticable sweeter sap. If I had all those trees, then I would end up with probably something MAYBE more like 30 ot 35 to 1, I suspect.

My best producer and sweetest tree is a younger silver maple that will out produce older trees by almost double.