LR cartomizers are not supposed to be used on slim batteries. You could damage the battery. LR cartomizers and atomizer (below 2.5) are for 450mah+ batteries
Forget 901 - I was disappointed in the atomizers - the way they leak juice out the side, the difficulty of cleaning the coil compartment, and the original manufacturer ones I had would rotate a bit barrel versus threaded end and then some kind of plastic armature in the coil compartment would block the side air intake and ruin the air inflow and the drag. If you really want to use 901, just use a 901 atty on a manual KR808D-1.
KR808D-1 is a real 3.7v mini. The manuals from Vapor4Life are like the original manufacturer ones, nice sized button and a threaded end that seems to be sealed inside. Then there is the newer rubberized style of SmokelessImage Volt, Halocigs G6, Bloogplanet Maxxfusion - the manuals have a totally sealed end but a very tiny button, and these batteries have a shorter cutoff of about 5 seconds but after flashing at 5 seconds you seem to be able to drag again immediately. I use both and I use plain Kanger KR808D-1 manuals (the newer gold button ones). These are nice. I recommend the standard aka 78mm batteries since the shorty aka 65mm battery is a very short charge of 180mah. I use Vapor4Life blank WOW cartos (around 2.5 ohm) and many like the SmokelessImage and Bloogplanet blanks (I think 2.7 ohm??) The only PCCs are flat cases. A DSE901 atty can be used on these if you want.
Joye 510 manuals - I love them too. I prefer the longer Joye 510 mega xl manuals (280mah) but during the day I use the short standard 180mah ones because I have a nice roomy PCC for those from NoSmokeVA. The only PCC for the 280mah is the Joye style plain metal non-roomy one. Nice totally sealed threaded end on the manuals. I use Boge standard resistance cartomizers on these and it gives a nice warm moist vapory hit. You could also use the 2.5 ohm ones if you can find them but those will use the battery charge up faster. I only recommend Joye and janty brand for good quality and to avoid inferior clones. At least one clone (FS510) is reverse polarity and will fry a normal 510 battery in its charger and vice versa. And one vendor called something 510 that is not even a 510.
I love the hotter drier hit of the KR8 as well as a the moister more vapory hit I get on the 2.8-3.2 ohm Boges on the 510. The 280mah aka 320mah KR8 is about 120mm w/ a carto, the 280mah Joye Mega Xl is 128mm w/ a carto.
