Sounds like valvetrain noise.
Piston slap on Japanese engines only occurs with loose-clearance pistons like aftermarket 2618 alloy pistons for force fed applications, and only while cold. You're definitely not hearing piston slap, but it could be coming from that relative area.
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'10 PW 370Z 7AT - wife's car - Project Raspberry Cheesecake
'08 Evo X - built motor+trans | BB-X @ 32 psi | CH3OH | self-built+tuned - ??? WHP
'01 Galant V6 - built motor | GT35R | self-built+tuned - 550+ WHP (retired) |