For me personally, I get zero TH without nicotine. I've tried adding PGA, water, doing an all PG mix, I even tried cayenne extract (not recommended!) The only thing that I have found that adds anything at all is sometimes certain flavors (menthol, minty or cinnamon) will add hit. As far as steeping, I can't answer. I can tell no difference with or without nicotine as far as flavor is concerned, other than having a peppery sensation of the actual liquid.
When I mix my own, I always mix a zero nic batch to test the flavors so I don't waste and aside from some flavors, i have yet to get anything but sucking air out of them. A warmer vapor helps a little but I was using a dual coil with a zero nic 100% pg mix yesterday and nada. Zilch. lol It's depressing. If I ever decide to cut nicotine out completely, i'll have to stick with strong cinnamon or menthol type flavors.
