if you're using a pump it will probably relieve some works from it while its working but once you close the valve everything will tend to "pressurize" and oil flow will probably be inconsistent. I don't see why bother. actually I think it whould be better now that I thought it through... if you use the pump alone it has to fight and overcome the muffler's prussure to be able to inject the oil to the muffler. BUT if you connect a line from the tank to the muffler the that will balance the pressure in the system. the pressure (lets call it #1) coming from the muffler equals the pressure #2 so now instead of the pump having to fight pressure and push the oil through now it just needs to push the oil since it has the same amount of pressure coming from the muffler to the tank and virtually elimimating pressure to to the pump and making flow MORE consistent!! Hope you understand and helps!!