I'm asthmatic and have very sensitive lungs. For 40 years I smoked weed but always suffered the consequences of lung irritation and congestion. When I switched to vaping, the effect was reduced but not eliminated. Then I found the Vapcap, learned to mouth-pull and started using filters to shield small particulates from entering my lungs. Now I experience no irritation. My vapor is super smooth.
Toking often is done by simultaneously drawing in vapor while inhaling it into your lungs. The classic joint toke. This can cause a lot of irritation and it's not necessary to get stoned.
Instead, try pulling the vapor into your mouth first, similar to puffing on a cigarette or drawing liquid into your mouth using a straw. Cover the carb of your Vapcap to restrict air flow, pull some vapor into your mouth but do not inhale, yet. Imagine that you are sucking up a thick milkshake through a straw. Once the vapor is in your mouth, near the end of the toke, uncover the carb momentarily, then open your mouth and inhale the cooled mouth vapor along with fresh air into your lungs. No need to hold in the vapor endlessly, it enters your system instantaneously, so you can exhale in a reasonably normal way.
This technique has been a total game changer for me and the pleasure of vaping weed is now JUST THAT; pure pleasure!
The third and final element has been filtration. Someone here on FC got me on to this. Sorry, I can't remember who. By adding a tiny disk of degummed hemp fiber to the bottom of my bowl, tiny particles that otherwise escape into the airflow are filtered. No particles in the condenser means no particles in your lungs either.
That's it. A simple technique that only adds to the blissful joy of vaping!
I hope you try this and that it heightens the experience for you as well.
Here is a link to making a degummed hemp fiber filter.
http://fuckcombustion.com/threads/best-of-dynavap-vapcap.24345/#post-1115563