The factory high press fuel line is a significant restriction. Especially when upgrading the high pressure fuel pump. In order to get the most out of your fuel system you will need to up grade the high pressure line running from the HPFP to the fuel rail. These lines are modified brand new OEM Honda fuel lines. Extra care is taken to make sure that flow is as high as possible while maintaining proper fuel pump control. This includes adding an optimal angled taper at the opening of the fuel line. Each fuel line is reamed to a specific size with a carbide reamer. This ensures a smooth finish allowing the least restriction while maintaining a size conducive to proper high pressure fuel pump function. We have tested many designs and sizes in order to create the best possible result. If you want the most out of your high pressure fuel pump look no further.