New 12 mm injector pump fuel lines causing me problems

[Ben-e-boy]

I did a fair bit of research before upgrading from my 10 mm pump to a 12 mm pump in my Gq and no where did any one say anything about the difference in the fuel line diameters and the issues of trying to fix it so I can get the full potential out of my pump

Generally that doesn't cause an issue. What is the actual problem