Smallfish, please post some links to peer-reviewed scientific studies supporting your positions, all of which are wrong. There is no evidence supporting your claim vital capacity can be increased via excercise. Even if it could be marginally increased, this does imply performance would be increase.
However, by praticing beathing techniques, more residual gas can be expelled, allowing for more complete transport of carbon dioxide.
Don't need scientific studies, just get out a medical textbook. I said vital capacity, not inspiratory capacity. That is the total amount of air you can get in AND out - the "useful" volume.
And, by the way, you can also increase inspiratory capacity with training - ask any free diver. The alveoli in the lungs are not always fully open, even under stress, and with training, more can be opened, allowing more gas exchange. Also, the vascular bed is increased with with training - just as it is in the muscles.