Dad and I drove up north yesterday to pick up my DN660. We are very impressed with the results. Worth every penny! Tested it in a round of frozen 18" oak when we got home.(now that's some hard wood) The rpm's stayed right up there along with the torque. Currently using a 24" bar with full skip chain but I think a full chisel on a bar this size would make it cut even faster. It was like being a kid at Christmas all over again