Practiced today.
Replaced my AE 72T spur with a new AE one.
Replaced my Robinson 33T aluminum pinion with a new Robinson steel.
Transmission sounds the same. Motor plate screws aren't overtightened, as the transmission spins free.
Going to take it apart tonight and see if I can find something. This kit is brand new, and it was noisy out of the box.
Side note, JC Barcodes V1 & V2 are amazing tires. Probably going to be my main tire to run at my track from now on. Once broken in and sauced, the V1 is nice when the track is slightly wet. The V2 is great in the dry.