GM powertrain engineers said the bolts will not need retorquing. Each LS1 piston is 6 mm shorter than the LT1's and weighs just 15.38 oz., which helps the engine rev more freely. The oil pump is mounted on the front of the crankshaft. This crank-driven pump is more efficient, using less energy to move the oil, particularly at low speeds and cold starts. The new camshaft is again made of steel, but it is a shorter, stronger unit.
Larger journals reduce unit loading, allowing for more aggressive cam profiles.
The cam's center has been drilled to reduce weight. A gap between the walls contains air and acts like a thermos. This retains exhaust gas heat on the way to the catalyst. Perhaps technical illustrator David Yimble summed up the LSI best. He should know.