I had them remove the oil injection system on my Johnson two stroke when I bought it-the dealer encouraged me to do this as the OMC systems were known to fail. Mixing oil is a hassle but the motor has performed flawlessly for 11 yrs now.
If you do disconnect the system be sure and disconnect the warning light and buzzer as these will go off when it thinks the engine is not getting any oil. That warning buzzer is LOUD. Ask me how I know.