Quote Originally Posted by jsn9333
However, the only way to truly answer your question would be to find a lab with a fancy gas spectormeter (or whatever device can measure THC in smoke).

Either way, I would not recommend holding hits in even if you do get higher faster. Sure, you might get more THC... but damn... you sure are putting a lot of cancerous tar and poison in your lungs at the same time.

Get a vaporizer and hold the hits in from that, if you want to truly maximize your THC inhalation without sacrificing your health, especially if you are a frequent smoker. I feel like I get twice as stoned if I hold my vape hits in. And it isn't just being dizzy from holding my breath like someone said above either... I actually get more baked and stay more baked if I hold in my vape hits.
A properly set, quality vaporizer will yield a THC vapor content of 95% and no toxins (thin white vapor). Obviously, this makes it literally harmless for holding your breath on. Any other device of direct flame gives you a far smaller concentration of THC (a Bic lighter seems to generate temperatures of around double the point at which the plant starts to burn, thus destroying much THC on contact) and a far higher carcinogen concentration. It's probably not a good idea to hold in bong/pipe/joint hits for longer than ~3-5 seconds. Somewhere at NORML there is a paper about, among other things, the actual concentrations as measured by their instruments that demonstrated bongs to be less effective than pipes/joints (in the sense that bongs had a higher carcinogen count per THC count [more tar less THC] than pipes/joints). Also, remember that cannabis per weight has roughly twice as many carcinogens as tobacco, and carcinogens do adversely effect the respiratory system.