Gaskets. At a glance they seem unimportant, yet without them, fluids would leak from every joint, fuel would spew, and flaming gases would explode from every crevice once the spark plug flashed.
Bolting on an aftermarket intake manifold has long been the introduction to hands-on hot rodding. Improved looks, performance, and, often, fuel economy can be just an intake swap away. Not to mention ...