I rarely apply the flame straight down into the top like you mentioned gibran.  I've always pointed the flame into the inner part of the cylinder, but tried to hit the inside wall of the cylinder with the tip of the flame, thus radiating the ambient heat that comes off of the flame down into the vapor chamber because I found out very early on that when I was vaporizing herb that aiming the flame directly down into the top peice will torch your herb.  And i only put a small amount of herb in there at a time because overfilling will also cause the herb to turn black and taste like burnt popcorn.  I came up with this sort of indirect heat approach to adapt for vaping herb.  I've had amazing results vaporizing DMT this way as well. 

Maybe my torch is just too hot because it seems like i have to use the indirect heat approach to get the best results.  And don't get me wrong,  i love this pipe for both herb and dmt.  Using the method that i described keeps me getting straight vapor hits for days without ever toasting my herb,  and my DMT vapor pulls are just as efficient.   There seems to be enough heat coming of of the flame into the inside of the cylinder that as long as you keep a steady flame in there you will always have enough heat to vaporize all of your spice.

I'm going to give your method a shot with the DMT though. Maybe even tonight.  I wasn't even looking for advice and ended up getting some great advice!  Much love!