Few bike upgrades—if any—comes close to the value of great tires.
It was one of my main reasons to get myself WTB Byway, two years ago. And, for the most part, I was happy with the tire. Granted, it has few quirks; it was occasionally losing grip when wet, and it was nightmarish to install, especially when I had to deal with it in the dark, under the rain, alone. But the high-volume carcass provides extra comfort, and the slick centerline rolls smoothly on the road. It must be one among the fastest allroad/gravel tires out there, too, I had thought.