Mostly any injecter line will work fine. If the line needs to be bent use some heat so it bends easier. Then cool it down and flush it out. That way no material that breaks off inside it will ruin a good injecter. I would not use copper tubeing either in case you were thinking about that. I would use some brake line because its capable of holding the high pressure of around 2000 lbs in the brake systems with hydroboost.. The common vacuum assist brakes on our vans and trucks is only around 1000 lbs of pressure in the lines.