FWIW: Antenna efficiency and SWR are not directly related. A good 50 ohm resistor can have a perfect 1:1 SWR and radiate nothing. You can reduce SWR at the rig by using a log lossy feedline. You'll get lower SWR, but also lower efficiency. SWR is important for two things, the rig's ability to drive the load at full power, and how it affects losses in feedlines. Properly lowering SWR is definitely not a bad thing, but may not directly effect the efficiency of an antenna.