Front Catalytic Converter - 1991 300ZX Z32

When sourcing Nissan 300ZX Z32 front catalysts in the junkyard, target 1990-1995 Twin Turbo models exclusively—Naturally Aspirated VG30DE engines utilize completely different downpipe geometry without pre-cat assemblies. The VG30DETT utilizes paired front catalysts mounted directly to the turbocharger outlets; LH (20810-40P00) and RH (20810-40P10) are mirror-specific and cannot be swapped side-to-side. Inspect the turbo flange sealing surface for warping or cracks, as thermal cycling commonly erodes the cast iron mating face. Check for oil saturation indicating turbo seal failure—these substrates easily clog when exposed to burning synthetic oil. Verify both O2 sensor bungs are intact (pre-cat and post-cat); 1996 OBD2 models introduced additional monitoring bungs incompatible with 1990-1995 ECU wiring. When removing, support the turbo assembly before unbolting; the flex pipe section between cat and main exhaust is often rusted—penetrating fluid on the 14mm turbo nuts is mandatory to prevent stud extraction.