There's many things you can do with this to open the airflow and still retain the flavor and vapor.I just got the Bellus last night. I just wanted to make sure people thinking about buying this tank know that this RTA has pretty tight draw. The Bellus is not like Crius or the Cthulhu v2 or the Aromamizer with a nice open draw. I drilled it out so the air holes are double what they used to be and it still has a much stiffer draw than the tanks mentioned above. The only way to get the draw to be wide open is if you put in 2mm coils in it after drillling it out. BTW I am not really into super airy draws....for example I vape the Cthulhu v2 with the air holes half way closed. The problem with the Bellus is that the if you place the coils in front of the air holes it severely restricts the airflow. But if you raise the coil it either shorts out or the flavor diminishes big time.
If you like a stiffer draw this is a great RTA. It has great flavor and produces very tick vapor. I wanted it for its single coil option. But for me the draw is way too stiff.
Using less cotton being one of them. Cutting back the thickness of my cotton helped a ton (just removing the top and bottom layers of my Japanese cotton.)
You can also raise your coils just enough so that you can see the bottom half of your coils thru the airholes. This should not decrease flavor, for me it's actually increased the flavor. The tanks/RDAs with best flavor usually have airflow hitting the bottom of the coils anyway.
I have a dual 24g 2.5mm ID build coming in at .29ohms. Bottom half of my coils can been seen in the airholes. It feels slightly tighter than breathing in normally.
To be fair, I've been using an early review version for about 3 months or so, so they might have closed the airflow a bit in the production model. Hope that helps.