I smoked for 30 years or so. Quit around 7 years ago. I believe my lung function has improved from what it was. I still huff and puff on the hills in northwest Arkansas, but I make it to the top. On the Big Dam Bridge century in Little Rock, I managed to pass a few people going up the big climb of the route. I averaged 15.2 on that ride, so I may be stuck in that range like you and some of the others. I'm a choir boy, and I've noticed an improved lung function in that endeavor.