  Recent studies by one of the present authors along with his collaborators in
[1-4] show that there exist the so-called open string pair production for a
possible simplest system of two Dp branes, placed parallel at a separation and
with each carrying different electric flux, in Type II superstring theories.
Further this pair production can be greatly enhanced when a magnetic flux,
sharing no common field strength index with the electric one, is added,
implying then $p \ge 3$. Given this, one may wonder if further enhancement can
be achieved by adding more magnetic flux(es) in a similar fashion. In this
paper, we explore this possibility. It turns out that adding more such magnetic
flux diminishes rather than enhances the pair production rate. This actually
implies that the largest enhancement occurs at $p = 3$ when the same realistic
electric and magnetic fluxes are applied for all $p \ge 3$. Curiously one of D3
branes may be our own world and if so, the enhancement gives a possible
opportunity to detect the pair production, therefore to test the underlying
string theories.
