I've pulled 68 cars on the first level of my Laggan sub layout with 1 Kato SD90. There is only a very slight grade, about .25%, and quite a few curves. I've never tried to see how many they will pull up my hill, it is a 2% grade, but I do have 2 grain trians with 1 SD90 on the front, 20 intermountain grain hoppers, and another SD90 in the middle, then another 20 grain cars, so I know they will pull at least 20 cars up a 2% grade. I think they might be able to haul about 25 up the hill. I'll try it and leave another post.