Nhaler megas, vapor4life coolcarts, vapornine turbos, and vaporsheaven boge soft caps are all 3.1-3.4 ohms. I use @ 5+ volts and they're excellent. (For KR8)
If you're looking for 510, Litecig 510 boge soft caps, and ikenvape has a good selection of diff resistances.
Hope this helps!