There was two different 4-2-1 exhaust manifolds, one came with the Mazdaspeed variant and the other a simple cast jobby by comparison (just as an fyi).Looks to be a FSZE to me. Resonator box on IM is the first hint. Compare the exhaust manifold to your FSDE. The FSZE should be 4-2-1. Did you not feel the difference in power delivery compared to the red mobile?
The differences between the FSDE (AU/NZ spec) vs FSZE (pre July 2002):
FSDE = 131hp @ 6000 / 126lbs/ft (174Nm) @ 4000 / Compression Ratio 9.7:1 / Redline 6500
FSZE = 168hp @ 6800 / 131lbs/ft (178Nm) @ 5000 / Compression Ratio 10.4:1 / Redline 7000
FSZE should also has different ECU to your SP20. And cannot be swapped around (different engine loom). Different intake cams also. Exhaust cams are the same (AU/NZ spec).
So in other words, start swapping everything over from the red to the blue NOW!! (drinks)
The looms are the same pending awd iirc. Intake cams are the same between DE (AU/JDM/NZ) and ZE though