Grams Performance Design offers high - flow fuel rails for the popular 6.2L LS3 and L99 engine.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.