They go into some detail of the build in HPP mag; read it last month. Butler made this thing to promote his new all-aluminum block. Too bad he's such a dick about the "new" Pontiacs. Just for fun call him and ask him to make something for, or do some work on an L67 motor. Last time I called he got all insulted I even asked. I used to buy a lot of stuff from them years back when I had my 428, and now I call and he turns his nose up to me. Sorry, just venting...