Amen! There is nothing wrong with putting in some extra work to make you stand out. The OP needs to decide if he wants short-term or long-term benefit. If he wants his reward now, then he should try and negotiate a reward. If he can settle for later, he needs to see this as an investment.
My personal anecdote: I started out about 20 years ago as a tech support engineer. We provided tools to customers and asked them to run a set of diagnostics before sending product back. The tools were written by engineering and totally incomprehensible for regular customers (hit ctrl-shift-F11, then fill in some hex stuff and read bit 7 for the result).
I wanted a better tool, so I set out to write one. Instead of writing the full implementation, I wrote a mock-up in my own time that showed the user-friendly interface and some basic stuff. My tech support boss was very happy and let me write the rest on his time. My tool became the standard for customer diagnostics for a long time. I continued to write other tools as well.
Eight years ago the company closed my office (I was the last person out). I bought the local lab equipment from them. After 6 months they called me if I could modify one of my old tools to support new products. Sure I could! I became a contractor for their tools. And even to this day I make a nice income on the side supporting their tool sets. The experience I gained has helped me a lot in my career, I landed a number of interesting jobs because of the initial effort and investment I made 20 years ago.