EFI return line, use emissions return?

Bill, the link worked! :)

If left with no other options, this would be a bolt-on solution! Having said that, the price is 61$ and 46$ to Norway.. then there is import tax and declaration fees... so modding my existing sending unit would be a more economic option.

But thanks a lot for the advice and link annyway! :)

I wouldn't be to concerned about swaging that 1/4 pipe, any restriction is more likely to come from the diameter it self rather than turbulence from an abrupt transition in diameter. A bit surpised you got as much as 9 psi backpressure in the return line, but as long as you still get the correct supply pressure to your carb, I wouldn't worry too much.