5th cell location

First of all, please don't tell me to do a search. I have. I did a lot of reading on this board and others, but I still have a question.

I have read about the wiring in other topics, but I was wondering where the best place to mount the battery was? I want to it to affect the handling the least possible. I have seen it glued to the body roof in the center. Does this make the car more likely to flip?

how about mounting it over the rear wheels on the chassis?

do I need to move the side, stock batteries at all to offset the location?

while on the subject does moving the stock batteries make that much of a difference even before adding a 5th cell?

BTW, I feel a lot safer doing 5 cell than 6. I just don't want to rish buring anything out. Can someboday give evidence for just going ahead and doing a 6? I think the extra weight and battery location would hurt handling ecven more?

thanks,
John