[magno_grail]

Of course OEM would be preferred, however, the price of two converters plus installation exceeds the value of most Boxsters this age. Plus, you would have a hard time selling a car that does not pass emissions.
CARB jokingly says that the converters are designed to last the life of the vehicle. In this case that would be true, the car would be junked unless you really want to keep the car.
The Valina converters meet the CARB requirements and are approved, although not if installed.
Inspectors here never physically check the converter or put the probe up the tail pipe, only go by the OBD2 test. OBD1 cars are sniffer tested because they do not have the second set of O2 sensors.
Pelican sells many parts that are not OEM but are equivalent. Does everyone only buy the Porsche parts?
Checked again, there are 35 converters on the CARB list but only two possibly fit.
Should note that shops are not likely to do this as it needs a jig to hold the parts in place for welding and they would have to be able to weld stainless steel. It would be like asking them to swap out the EEPROM chip in the immobilizer from your old one so it would not have to be programmed for your old keys.