I'd be curious in the results as well, but is there anything keeping you from doing a DP?
CA Smog laws have never stopped me. Keep your OEM Downpipe, and when your 6 years from new is up and you need to get smogged, swap parts and tune, get smog, swap back for another 2 years.
Don't get pulled over doing anything stupid in the middle of all that, and you're fine.