SKUNK2 ULTRA SERIES RACE MANIFOLD PRIMARY FUEL RAIL BLACK HONDA B-SERIESEngineers at Skunk2 Racing have developed primary and secondary fuel rails for the popular Ultra Series Race intake manifold. Skunk2's newest fuel rails are made from 6061 T6 aluminum, features large 0. 669 inch internal bores and 8 AN o ring thread, and can support up to 1,200hp. Note: Supports Up To 1,200 HP 0. 669 Internal Bore 8 AN O Ring Thread Compatible with E85 and Methanol Requires the use of an external regulator.