Fortunately (or unfortunately, depending on how you look at it) for those with piano OCD, there are not that many tweaks you can do yourself to your piano. Of course, if you happen to also be a tech, then you can regulate, tune and voice your piano until there is physically no further improvement possible.
But there are two major piano tweaks that you can consider, if you really really think that you can’t live with your piano in its present condition.
The Wapin bridge is actually a re-work of your piano’s existing bridge’s pins. Practically all piano manufacturers angle the bridge pins slightly in towards the strings. This is to ‘trap’ the strings so that string vibrations don’t cause the strings to gradually work their way up and off the pins over time.
The Wapin system replaces the angled pins with vertical pins. It is claimed that by using vertical pins the strings are allowed to vibrate more freely, giving clearer fundamentals and partials, and longer sustain. An angled third pin is inserted between the two usual pins to provide the required string trapping.
In this tweak, the action for each note is analysed and then adjusted so that the touch is ultra-even across the keyboard, with static and dynamic touchweights set to what you want. The action parts for each note are weighed and measured, and the geometry analysed. Minute adjustments to the weights of individual parts and to the geometry are done, and the friction of the action centres are normalised. Here are the ‘before’ and ‘after’ weight and friction graphs of one particular piano.
Whether or not either of these tweaks are meaningful in a high-end piano is subjective, and also subject to the law of diminishing returns. This is somewhat like high-end hifi. How much are you willing to pay to squeeze the last iota of performance out of your system, and can you even hear it? I’m not saying that these two tweaks don’t work. In fact, I think that they do. What I question is whether or not they make me a better pianist.