Definitely parallel. 70w with one cell, 100w with both in ☺TC100W would be series buddy to reach that wattage.
Can't think of any regulated parallel external cell mods, sorry mate.
If you don't mind built in, the Kanger KBox 70w.
It's 4,000mAh
And with 20% off at slowtech tomorrow it'll be a steal at $30The Istick 100w TC is parallel. Tidy little mod too.