Exponential function analogue of kloosterman sums

We consider exponential sums of the form K_g(a,b) = ∑ _{x=1 gcd (x,t)=1} ^t exp (2πi(ag^x + bg ^x-1p), where g is of multiplicative order t modulo the prime p. We obtain a nontrivial upper bound on these sums on average over all elements g of multiplicative order t, provided that t ≥ p^3/4+δ with an arbitrary fixed δ > 0.