(Yesterday) Compact, oversized handlebars, a stem, and bar tape.
I had experimented with a longer stem, the length of which I liked, but I was not happy with its highish weight, lowish stiffness, and potential unreliability.
Having decided that I was going to buy a new stem, I decided to upgrade the bars too. The old stem/bars on the bike in question were noticeably flexy compared to the oversized parts on my CAADX. I also prefer compact-style bars with easier reach to the hoods and drops than the old-style bars I had been using.
I bought some new bar tape as well. I am going to reuse the old tape on a singlespeed bike that I am putting together. The old bars will go on that too, but not the dodgy stem. I have another that I will use instead.