We give a new construction of tensor product gamma factors for a pair of irreducible
representations of
and
.
This construction is a finite field analog of a construction of doubling type due
to Kaplan in the local field case and due to Ginzburg in the global case,
and it only assumes that one of the representations in question is generic.
We use this construction to establish a relation between special values of
Bessel functions attached to Speh representations of generic principal series
representations and twisted matrix Kloosterman sums. Using this relation,
we establish the multiplicativity identity of twisted matrix Kloosterman
sums.