Which coffee is it? V2 Platinum coffee is high PG. XEO Coffee Arabica is 50/50. I haven't vaped anything that high in Ohms in a very long time so I'm not sure 50/50 is going to work for you. But, coffee flavors do have a tendency to taste burnt. Also the more PG you have in your juice the harsher it is going to be for you. And the more nic you have in your juice the harsher it is going to be for you. First you're going to need to find the PG/VG of your liquid. You know the nic, that's a good start. I have found that 1.30-1.80 Ohms resistance works really well for me on a 50/50 blend at 12-18 mgs nic. You can get cheap cartomizers all over the place, by the way. If your battery has eGo threading:
Here's one from MVS:
Innokin iClear16D Clearomizer
With replaceable atomizers and you can pick between 1.5 or 2.1 Ohms:
Atomizer Head for Innokin iClear16B, iClear16D
Thanks, listopencil. You've helped a lot. I appreciate it. See my post above.