Change of exhaust header vs tune

Bit of an odd one but just saw almost 10% fuel trim difference between two banks (4cyl) show up after the introduction of a equal length header on a stock ECU. N/A car.

Reasonably comfortable there are no leaks and no reason to believe injectors or coilpacks suddenly sprung an issue.

So, is it possible that I have to add a % compensation on one or both of injectors 1 and 4 using a piggyback to add more fuel? To even it up again?

Or just accept that the fuel trims will sort it out and stick with stock?

The car will get an ECUMaster or Adaptronic (undecided) when more built but for now?