cab, what were the results of the 558? From what I understand 20% of your power force is used up right after TDC firing, so what is better, a short stroke with each cylinder firing closer together or a longer stroke firing further apart with fading energy on the longer down stroke, but with a little more energy at TDC than the short stroke? I don't know, but this stuff is very interesting to me and I would sure like to know. To me , the longer strokes are fine as long as you can get a long rod in there. There are plenty of engine builders building long stroke motors that work and that's fine buy me. I have no issue with it. I still think for me personally, a 470 is a design of my better liking. I said this before, the Japanese build some pretty bad ass inline 4's. I had a couple. The last one was an 08 gsxr750 that I did a little super tune on. It made 140hp to the rear wheel and was almost scary to ride. 48.7mm stroke, not sure what that is in inches, but its very short, under 2". I understand torque moves the object and maybe the name of the game, but there are other things that come into play that pull it down a bit imo. no disrespect here to anyone, just try to learn.