Ok, time to make my $.02 in the most obtuse way possible.

1. Joints will never be as effective as vaporizers/bowls.
2. Debating how to increase potency of a joint is futile in nature.
3. Vaporizing of THC takes heat + time, not just heat.
4. Too much heat is going turn THC into Carbon and some noxious fumes in a chemical reaction called fire. Vaporizers will achieve the most efficient high because no THC is destroyed.
5. Joints are, in fact, a waste of herb as they burn continuously rather than being snuffed out after a hit like a bowl. Whip style vaporizers continuously heat and vaporize BUT because you cover the mouthpiece is stored for later (Plus without hot air rushing over, it's pretty cool when it comes to the herb itself)

Also, water filtration filters out a little bit of tar, but also THC. Also, it filters other non-tar particulates thus, the thick smoke is mostly Tar. Whether it's equal in health issues or worse in comparison to joints is neither here nor there because those roaches are like 50% tar and 50% herb...

Finally, TAR DOES NOT GET YOU HIGH FROM THC!!! You suffer oxygen deprivation instead. It's like sucking on a tailpipe intentionally. Evidence is clearly anecdotal at best but there is zero fat in tar for THC to rebond to. THC also will restabilize in the air hense why you can only store vapor in a volcano for 24 hour.

If so facto,
Joint = x, roach = .25x + Nothing from the tar. Joint = Roach + .75joint. x = .25x+.75x = 1(x) = x, THEN x = x, no better, no worse.

Back to my bowl.