Conjectural square-root cancellation for twisted Kloosterman correlation sums

Let $q$ be prime, let $a$ be an integer coprime with $q$, let $\boldsymbol{b}$ lie in the generic set

$$\mathcal{B}^{\mathrm{gen}}:=\mathcal{B}\setminus\mathcal{B}^{\Delta},$$

and let $[?]$ be elements of $[?]$. For the correlation sum $[?]$ formed using $K(x)=\operatorname{Kl}_2(ax;q)$, Conjectural correlation-sum bound. There exists a constant $C$ such that

$$|\Sigma(\boldsymbol{b},\mu_1,\mu_2;q)|\leqslant Cq^{3/2}.$$

The bound expresses the expected square-root cancellation in the non-correlation, generic case for these sums. The statement is presented as a conjectural estimate and no resolution is supplied in the source.