Parallels are a good choice when it comes to vapor production. If you're talking about competition, build as low as they'll let you (Or as low as your battery can handle pulse wise if there is no restriction, do NOT go over your pulse rating. You can probably get away with it a few times without detrimental results, but this isn't something that's worth risking life and limb over, and .... will eventually happen). Also, lift your
coils up a bit and use very little cotton (Enough to go from the coil to the deck, no cotton should be under your coil so that airflow can get all around it). I've also seen people that have good results with 18-20 gauge kanthal (simple micro coils) or gplat/similar wire. Centering your coils helps a lot too, since it makes it easier for you to line your airflow up perfectly & hit the coil head-on rather than at an angle.