The 901 has different airflow and expects its atomizers and cartomizers to have an airhole in their SIDE as an air intake. I saw 901 cartomizers one time - real 901 cartomizers with an air hole in their side (which hopefully would not drip as much as the hole in the side of their atomizers). Sorry - I don't remember where I saw the 901 cartomizers.
Hopefully somebody can tell you if there are any brands of KR808D-1 cartomizer that get good airflow on a 901. And does anyone know who sells those 901 cartos?
Also note - the nice 901 PCCs I have seen did not accept manual batteries. Manual batteries are harder to damage/kill with liquid leaks, can't accidentally turn on in wind or vibration, make it easier to get the best hit every time.
Re voltage - KR808D-1 is 3.7v and hotter fresh off the charger (the rubberized models are 3.6v regulated). 510 is more like 3.2v, maybe 3.4v. I vape both - 180mah 510 manuals and 280mah V4L long-cutoff manuals. It's hard to find many cartos closer to 2.5 ohm (single coil) for 510 so I use 3 ohm so that is a cool vape unless I move the carto to a 3.7v mod or fat battery (then it's warm). For KR808D-1 there are easily available 2.5ohm-ish cartos - V4L WOW cartos and the nice 2.6ohm bottom
coils from Bloogplanet and SmokelessImage (BTW - also look at their KR8 PCC - not metal). 2.5/2.6 ohms on 3.7v is nicely warm for a slim ecigs - can even get hot on the lips which is why I use a delrin drip tip as a mouthpiece.
I do not know what voltage 901 is.
BTW I think there is a DSE901 forum in the Model-Specific section of ECF. You could try asking there too (though I don't know how busy the forum is).