concentration would be roughly between 110-130mg/ml

2 carts = 75mg/ml (if you actually get all 50ml's out...)
most people get 42-43ml's out...so it's around 83-86mg/ml

Well if ya used an extra cart it'd be around 126-132ish...could be lower..

i'd actually add a lil' more oil to that mix...instead of trying to get 3carts in a 4g kit...

why not try 3 carts in a 4and a half gkit... Basically a 4g kit and half of a 2g kit...

would make it much easier...

If you do it as listed...the chance of pain/abcess/bruising increases a lot..

by the way, i'd check my math on the conversion, that was off the top of my head...