The Red Dragon 2-piece is KR808D-2 aka E9
You could try Greensmoke cartos or Smoke 51 Duo - those are the same model but they made have the exact same physical cartomizer type so they may not change your drag. You could also try the D2 cartos at leCig.com
To use all of the KR808D-1 stuff on your batteries you would need the D2 to D1 adapter from leCig.com. Then you could use cartos from Vapor4Life, SmokelessImage Volt, Bloogplanet MaxxFusion, Halocigs G6, as well as all of the blank KR808D-1 cartomizers 2.5 ohm to 3.4 ohm
If you are adding juice to your cartos, for the best drag stick to juices with 20% VG or less and mainly juices that are light and clear in color (less likely to leave carto-clogging flavoring sediment). And cartos have limited lives. They are meant to be disposable. I can get a week or more out of one but they do degrade. Only some succeed in washing and drying cartos to get more use out of them, and only some bother to try.
Manual batteries help get a good drag (you can press the button in 1-2 seconds before starting your drag so vapor is already being made) but I don't think you can get manual KR808D-2/e9.
I use a plastic or delrin 510/901/KR808D-1 drip tip instead of the endcap for a wider stream of vaper.
In general, I find my manual Joye brand 510 (180mah) and manual Joye 510 mega xl (280mah) with standard resistance Boge blank cartos and thin juices give a somewhat easier drag. (I press the button in 2 seconds early)
If you go to fat batteries and mods - I get an even bigger drag putting the Boge cartos on my Riva 510 from Liberty-Flights.com (they have the newer Rivas that are higher voltage than slim 510) and you can get an even bigger hit using the hotter 2.0 ohm Boge cartos on the Riva (you cannot use low resistance cartos on slim batteries)