I have the exact same build as you. IPV D2 Version 2 with the uwell crown. I haven't used the stock coils yet cause I immediately bought the rba section and am saving the stock coils for when I really need it (vacation, long trips, etc.) From what I've seen from reviews, the stock coil lasts quite a while, especially if you aren't vaping at high wattages. But the problem with that is the stock coil NEEDS high wattages to get the best flavor out from them. The D2 only goes up to 75 watts, which is kind of the minimum requirement for the Ni200 0.25 ohm coils for a great vape (according to reviewers). I use the RBA section, strictly using kanthal for now. Ni200 and titanium builds are not my thing yet simply because I have so much kanthal wire at home and I don't want to buy new ones. The stainless steel coil I literally just used on the RBA section was not great. The battery life drained significantly, even when using TC mode (titanium mode, 200 celcius, 20-25 joules). The coil lasted about 2 tanks before it started looking rusty and i decided to go back to kanthal power mode. First time i tried the RBA section was with the built in stainless steel coil at power mode and it had a funky taste. I do suggest using the RBA section, its not that expensive. Coiling wise, because the deck is considerably small, i would typically go with a 26g kanthal with a 2.4/2.5mm diameter coil, 5-7 wraps depending on your taste. Using the 28/30g wire will definitely get you above 1 ohm with 5 or 6 wraps. I like to vape mine at 20-25 watts, so i stick with 0.7-0.9 ohm range which needs the 26g. Wicking is not complicated, don't need to use the S-shaped wick, or whatever wicking method out there. Simply pull it through the chimney, cut it off right at the chimney, and stuff it down with a piece of your wire (using tweezers will condense the wick a bit, so the wicking won't be as efficient, leading to dry hits). Make sure it covers the juice holes, push it back a bit with tweezers or the wire to ensure juices can flow in. Been vaping on the crown RBA section for over a month, i found that this is the best build for me. No dry hits, no burnt taste.