If you want more power with less work this video, by international head specialist David Vizard, is just what you are looking for. With over 50 years of flow and dyno tests, plus smoke tests, wet flow tests, CFD tests and much more DV shows what to do and, equally important what not to do. If you want to pick up as much as 80 hp then what this video along with parts 1 & 2 is for you.