801 attys run cooler than others as their internal resistance is different. This means on the standard 3.7 volts, some people don't get enough 'hit' from them - though it depends a lot on your
e-liquid of course.
But if you get a 5 volt mod with 801 fittings, things are entirely different: monster vapor and TH as well, especially if you use liquid to suit this. Plus the big carts work well at high voltage as they hold more liquid between refills.
So it looks like you have three choices, if the 801 doesn't do it for you on your penstyle:
- get some
eliquid that gives more vapor and/or TH
- get a 5 volt mod body, to suit your 801 attys / carts
- go back to 901s and 510s at low voltage because they may work better with the liquid you are using
I'd go for #2 but it's a personal thing, only you can decide. Remember that if you buy a mod, it needs to have safety features as the big batteries up the risk - a kill switch, gas vents, and use protected batteries only.