I've been building for awhile now (almost a year) and I keep wanting to push the vape envelope. A little about my setup: I use the Defiant Designs DS, which is a squonking mech mod using two 18650's in parallel. The batteries I use primarily are VTC5A's, which I know are safe to use down to about .10. I also have 30 amp batteries for more serious builds (Samsung 20S) that should be safe down to .08, although I've never built that low yet. I've been struggling to find the perfect build after many, many attempts. I like lots of vapor, quick ramp up and cool down and I don't mind slightly hot coils, just not scorching. My current build is dual coils using parallel 26g/36g single core Ni90 Clapton wire from Lightning Vapes, 5/6 wraps, 3mm ID, .11 Ω in my CSMNT RDA (shown in pic below). Admittedly it hits pretty well, although the ramp up is not fast so I have to take loooong draws to get them warmed up initially, just to get a decent draw. The other types of wire I have on hand is 24g/34g single core Ni90 Clapton wire (which I haven't had much luck with) and Master of Clouds 24g Stainless Steel round wire. I'd like to use what I have to make something with low coil mass, high surface area and hits around 300 on heat flux (mw/mm²), which is what numerous users on Reddit keep telling me. I tried using the sweet spot option in the Vape Tool Pro app on my phone to help guide me in reaching that number, but I'm not sure if I'm using it right. One of the variables it asks for in that section is wattage. In order to figure that out I need to know my voltage when using ohms law, but I'm not sure what value to use, 4.2 (max voltage) or what reaches the atty after voltage drop. I went with the latter. So I measured the voltage reaching the atty posts under load using a multimeter and used that value in ohms law to figure out my wattage. Please correct me if I did something wrong: P=U²/R P=3.8²/0.11 P=131.27 I also noticed in the app under "Coil Calculator" that sometimes the resistance it says my hypothetical build will reach doesn't always line up with what I actually get, even after double checking all the variables are entered correctly. And not by just a little, sometimes it's way off. Sorry this is so long, just trying to give as much info as I can. So in summary, I'd like to know how to figure out the best setup for the wire I have as mentioned above and if anyone has experience with the Vape Tool app, how your supposed to correctly use the "Sweet Spot Option." I don't mind buying new wire if I have to, I just want to see if any of what I have is ideal for this build or not. Thanks for reading!