My company used to do physicals when we went to the training center for new product classes. After smoking on the way to the health screening my lung function test showed very slight restriction in small bronchi, but otherwise normal results. They said that was typical for a smoker. I'm sure it would be better today. My lungs are clear and I can tell that I have much better performance under physical exercise. I don't get winded like I used to. Just a year of not smoking makes a difference.
Those tests will make you see stars! I remember the nurse telling my to keep on blowing in the tube to make the graph stay above the line. I thought I'd pass out if it didn't stop soon. You tend to pray for the bell to ring so your can stop exhaling.