The Holley LS1/2/6 Lo-Ram intake manifold kits are designed for GM LS Gen III and IV engines equipped with GM LS1/2/6 (cathedral port) cylinder heads. These intake manifold and rail kits will work with OE (Original Equipment) or aftermarket cylinder heads. Holley Lo-Ram intake manifold kits include all the sealing o-rings, plugs, and fasteners required for the installation of the kit. The 300-601 & 300-601BK front-feed, base-lower intake manifold provides two injectors per cylinder for hi-volume fuel demands, flexible fuel supply strategies, and dual-fuel capability. Offering this base intake manifold with fuels rails separately allows you to select your components individually as you build your induction system. Complete top-feed manifold kits are also available with dual fuel injectors, see P/N's 300-624 & 300-624BK. The top-feed, short runner, low-profile base intake manifold was conceived to package with an air to water plenum mounted intercooler with a shorter overall height than possible with other existing intake manifolds. Top-feed throttle body tops are available as a machined casting 300-246 & 300-246BK which are configured for a 105mm throttle body, see Holley P/N 112-581 or similar models. The fuel rail kits come with two sets of brackets. A set for long (usually standard length) fuel injectors and a set for short (such as Pico, or LS7) fuel injectors.