Don't bother with rebuilding stock screw in coil heads. Yes they will vape better, but its very tedious, and in my opinion not worth the time unless you have a few bad ones around you just want to make good on. RTA's like the Fogger and Aqua are rediculous in my opinion. No vape quite like them, especially for direct lung hitters. For mouth to lung hitters go with a Kayfun. Can't get the airflow open quite enough on stock AFC (even with screw all the way out) on the Kayfuns for direct lung hits that compare to the Fogger v4/Aqua. Not to say the Kayfuns aren't great because they are, and going with any of the above mentioned RTAs will simply be in a whole nother realm in terms of flavor and vapor than any type of Aspire BDC, Natuilus, Protank, or Kanger. The builds are also much easier than a tedious 32g dual stacked coil single strand of 2mm silica build that you have to do on these stock heads. Not to mention taking them apart and worry about the insulators moving all over the place. Just not an enjoyable experience. But when rebuilding a true rebuildable RTA or RDA, its fun, and worth doing. RTA, RDA, all the way, without a question. Subohm on mech mods, these tanks are monsters. Obviously make sure you have the knowledge of safety if making those types of builds.