Grams Performance Design now offers high - flow fuel rails for the popular 5.7L, 6.1L, and 6.4L Hemi engines. Designed as direct OEM replacements, offering drop - in compatibility, Grams Billet Fuel Rails are the perfect compliment to our line of high performance fuel injectors CNC machined from 6061 billet aluminum w a large .669 internal bore for more consistent fuel pressure and volume to keep those high volume injectors happy - 8 ORB ports are added to each end of the fuel rails for easy access to fittings and plumbing flexibility.