BikeMaster's angled aluminum valve stems (bikemaster.com) seemed like they would do the trick, and I was impressed with the price: $20 for a pair. Swapping back to street tires, I cut the stock stems off and quickly installed the aluminum set. They're in two pieces, sealing with a rubber O-ring squeezed by a 14mm nut. BikeMaster sells them in five colors, including blue, but I had a hunch it would be tough to match the wheels perfectly, so I went with gold. I think it accents the gold fork tubes nicely. Plus, when you're looking for the valve stem on the wheel you want it to be easy to find! Checking pressures is easier now, with sturdier aluminum and the stem pointing the right direction. I'm sure it'll pay off at the next trackday as well as in the meantime.