I would say about 15-20% more. We have a 9790 and my uncle has a 8780xp. And that's what I have figured for a difference. The 9790 cab is a big jump. And the 9790 is a lot easier for daily service. We have the QSL 9 cummins. I would look for a sisu. We have had quite a bit of grief with ours. Very temperamental engine.