I discovered the Hipshot Tremsetter somewhere 80/90. I started to use them and found myself tighten the extra spring really hard to reduce slacking during bends. It worked really good but you really needed muscles to operate the whammy and that setup had a really nonlinear spring tension around the resting point. I used this solution for many years.
Some years ago I saw someone mentioning The Göldo Back Box. It was easier to install except that it had too little space for the screw driver when fastening it to the body of the guitar. I also found it a little bit more cumbersome to adjust. The test installation ended up with a problem. When I moved the whammy up and released it it did not manage to move the bridge to the same resting point as if I did a dive and released it. I therefore replaced it with the Tremsetter and I have not tested it since. Later I got the same problem, but less severe, with a Tremsetter, so it might not have been the Back Box after all. I still have two in possession so, who knows. I might give it a try again sometime.
The next discovery was the SuperVee Mag-Lok. It used magnets instead of springs. It did a really good job stabilizing the tremolo during bends and since the magnets only did it's magic in the resting position it did not require big muscles to operate during dives. It also was much more linear around the resting point. But after a while I discovered that I have gotten tuning problems. It seemed like it switched between the "correct" tuning and a slightly sharp one. It happened sometimes during dives and after some more investigation I realize that it was during really deep dives. You could also here a strange sound during these deep dives. I realized that the Mag-Lok tube hit the guitar body and forced the pin mounted in the sustain block to move up out of the hole. After release of the whammy it did not manage go down fully in the hole again. It therefore moved the resting point. I will redo the installation and put something under the mounting plate so that it never touches the guitar body. I think this be a small fix, I hope ;-)
Just a couple of days ago I found the Van Rosa Stay Tuned Tremolo Claw. After reading about it and seen some tests I got really interested. So I ordered a couple to try them out. It is said to be really easy to install and that it does the stabilizing job really well. Since it uses only normal springs mounted differently I guess that this setup will be really linear around the resting point as well. But we'll see :-)
Can't wait :-)
Rock on!