pstep

You also might check to make sure the torque converter is completely seated you have to spin it until you feel it click in 3 times

If the idle is good and no driveability problems are present the noise could be from the sla's they are always more noisy have you compared the noise to another sla engine the hydraulic dampen the sound alot so before going some where else also check the exhaust manifold to make sure that sealed tight