I checked my PCS last night.

Not the clearest spec book in any case. I found one section that stated FRONT spoilers are permitted and listed all the maximum dimensions, placement yada, yada, ect.

There is no mention of a rear spoiler. I would suspect that if it doesn't say you can, you can't.

The spec line for the RX7 DOES specifically states the OEM spoiler MUST BE REMOVED. Nothing on the CRX but I seem to recall hearing something at the Prod open house tent at the run-offs, so possibly a Fasttrack item?