I have done extensive testing with many different tweeks through the years and have come to the conclusion that some work extremely well, some marginally so and some with trade-offs that are not worth the effort. Top shelf tweeks include the following:
* AudioDesk Lathe Treatment with Marker Edge
* Bedini Ultra Clarifier preferably the 4 Beam
* Densen DeMagic and/or Ayre CD (for overall system)
* Mapleshade Destat Unit
* Mapleshade Optrix (used selectively)
Beyond these there are many other system tweeks that get into bases, cones, power conditioning, etc.
I personally believe that patiently tweeking a system is indespensable to getting all the performance possible from your investment.
One tweek that I would avoid like the plague is Mapleshade Silclear. This is a product which initially provides an improvement, but then gums-up (regardless of how thin the coating) and becomes a problem downstream.