One downside to getting access to a vehicle roughly 15 - 25 years after its initial release, is missing out on the chance to get some aftermarket parts. The ones that were made, are now no longer in production, or super hard to get a hand on. Luckily, some companies have stepped up, and are offering Aftermarket Parts for the C34 Stagea!
LF Industries offers a replica of the popular Tail Light Covers. You can purchase the Uppers Only, the Lowers Only, or the Upper & Lower Full Kit. They do come in an unfinished state, so sanding and painting will be required on your end, but the finished product speaks for itself.
MV Automatics offers a Stage 2 Shift Kit for the RE4R01A & RE4R01B transmissions found in the Stagea. Direct link to the product is in their name above. Located in Australia.