if you want more power without breaking the bank, the ego twist will give you variable voltage power with the same form factor as your KGO, same threading, and you can even use the same charger.
if you want a big battery mod with variable voltage, the best cheap bet is the vector over at vaporbeast....i recommend it because it is essentially a newer versoin of the young june lavatube that has deep enough wells for your ego cone threaded devices (like stardusts, etc.) with superior power and built in atomizer ohm reader, and gives a great price point ($75 bucks for the kit, includes two batteries, charger, case, two atomizers, and tube itself)...i will note however that the chrome version is the only one with the deep wells for ego devices, and costs more, but only by like 8 dollars or so....so it makes sense to just go that route....
either way you go, both of these devices would keep the same threading style as your KGO, the twist kit you can get at vapors choice for around 56 dollars, but for a few more you can get a big tube mod with WAY more power and the convenience of removable batteries....essentially, it is your call, your decision, and as always, YMMV, but both i can attest to being good starting level VV devices.
hope it all helps, welcome to ECF, enjoy your vape!