The LS Race single-plane intake manifold was designed for hi-performance/racing engine applications, 5.3 to 6.2+ liter displacement, and maximum engine speeds of 6000-7000 rpm, depending on the engine combination. This single-plane design provides optimal performance across the RPM spectrum while providing maximum performance up to 7000 rpm.  As-Cast Runner Cross-Sectional Area - 3.5 in² at the runner entry tapered to 2.9 in² at the flange exit  Throttle Body Flange - Standard 4150 for up to 1-3/4" diameter throttle bores The Holley LS Race manifold incorporates a split feature, which allows disassembly of the intake for direct access to internal plenum and port surfaces, making custom porting and matching a snap. With shoulder bolt locators and O-ring seal, reassembly is simple and precise.  A-B Height - 7.32" (0° carb flange angle) The new Holley Single-Plane Race intake manifold were designed with performance in mind. They feature a race bred, two piece split feature that was previously only found on the most expensive race intakes. The manifold will fit GM LS Gen III engines with cathedral port heads and are intended for 4150 style square bore flanged carburetors or throttle body EFI. Technical Data:  Port Size- 3.28" Height x 1.10" Wide