It took me a while to get all of my sway bar end links properly tightened too. I only installed them in the rear and left the OEM end links up front. Replacing those will be my next project.
As a warning to others... make sure you tighten the nuts on these properly before driving on them. I drove around on mine for a couple of weeks, while I tried to get things corrected and because of that, the thread on both bolts got smashed and the nuts would no longer tighten properly. I had to replace the whole thing with one of the extra end links I had for the front.
Also, in order to properly tighten these, you will need a special thin 15mm wrench. You need it to hold the inner flat piece, which holds the ball joint in place so you can tighten the nut.
You will also need a standard 17mm and 19mm wrench. I would recommend getting a ratcheting 17mm combination wrench, to make tightening the bolt easier. Having to remove the 17mm wrench each time to reposition it, while still holding the thin 15mm wrench to keep the ball join in place, can get problematic and frustrating.
Here is a link for the thin wrench set that I purchased.
Grip 9 pc Thin Wrench Set
CK