which dual cell should i do, laymans, external, internal etc

[eman1]

I want to do a dual cell mod to my spare bit charg 2 speed.
I have two stock batteries right now, and i was planning on using them with a new 2.2 i have. I also have a spare new 4.2 but that seems a bit much for a dual cell. I will try it though.
I want to do an internal dual cell, but i think there are too many risks involved with that. I have heard that the laymans dual cell is good, but it has less ?amps? How does that affect the way the car will perform?
I might just do an external dual cell. I know how to do it, ive read quite a few tutorials on it. How much will my car roll with the cell up high?
My MS pro has the full pullback wheel mod, i could always take those tires and rims and put them on the dual celled car.
Or i could just use the stock tires, or i could do a fullsize wheelmod. I will do whichever doesnt flip too much.
I kinda want to keep the pullback wheels on my MS pro so i can still race with my friends with that.

So, should i do the internal dualcell(im afriad to do this) the laymans dualcell, or external?
And how much will the car roll with the external dual cell.
And what are the cons of the laymans dual cell vs the other two?
Thank you!