GVG works great for Changa with me, I got it down first time so it can't be that hard  . It does have to be 1:1 in my experience to get the most 'bang' out of it. Also never had a problem with vaping freebase harmalas in the GVG on their own or in Changa.

Just start off with the torch 1-2cm above the ceramic plug, move in circular motion and move the heat gradually further away from the bowl until you have filled your lungs. Bish bash bosh, easy peasy :thumb_up:

I also find using conical gauzes like this make a huge difference as it keeps your dose directly below the heating element, rather than having some under the glass rim of it not getting heated properly:

(Basil Bush 'conical gauze') Enjoy