To all you guys that want it to break the sound barrier remember. One It was designed to haul freight which were slower than passenger set ups. Tw0, you are forgetting the massive amount of heavy horizontal iron you are making run in circles which it doesn't naturally want to do. Thus you could destroy it at sustained high speeds. And speaking of heavy iron, you have to be able to stop it. Don't forget that detail. So run it at about 60, 65 and it will run all day for you every day and keep it's iron where it belongs. If not, think about taking part of a side rod up into the cab if it clears the fire box on the way up.