The father-in-law and I are going to build a splitter in the next couple of months. We usually rent one from a friend of his. It may seem small, compared to the talk here, but there is nothing it hasn't been able to split, and the two-stage pump only kicks in if you get into some narly, twisted stuff, or a big knot. the rental one has a: - honda 5 hp - john barnes 2 datge pump (I believe about 11gpm) - 3.5" cylinder with 1/5" rod, 24" long. As we already have a 4 hp honday engine we can use, we are planning on just getting the same size pump and cylinder, as the one we have been renting. I realize they say you need 5 - 6hp for an 11gpm pump, but our experience with it says that the 5 hp honda is only running about mid-way (or less) between idle and full throttle, so we figure that the 4hp should be fine, with the engine revving a bit higher. Any problems with our thinking? I am sure the cycle time would be faster with a bigger pump, and engine etc but the 4hp is free, and the rental one seems fast enough for us. We are planning to make it horizontal only (have strong back / weak mind and a wood hauler with lift for the really big stuff) and I like working at waist level, with the side tables.