Actually, making power with propane is a little cooer than doing it with diesel fuel alone. For example, if a stock truck makes 190 rwhp, doing that with a mixture of propane and diesel will be cooler than doing it with straight diesel. However, with propane, you're capable of making a lot more hp, so doing that makes the truck run hotter. If I'm blasting up the 12% test hill, my speedo, tach, boost gauge, and pyro swing from left to right in unison, like the Rockettes.