What tune do you have?
Other's have posted they don't pass smog in Cali with a tune and test pipe but one of the venders here insist their tune passes smog in Cali.
If you do flash back to stock, you'll also need to do the emissions driving cycle to get it to pass.
https://www.smogtips.com/smog-questi...es-Drive-Cycle
How to Perform a BMW 3-Series Drive Cycle
Begin by: (Make sure you have between 1/4 and 3/4 fuel in the gas tank. The EVAP test will not run while your BMW has a full tank of gas or the gas tank is near empty. Ensure there are no pending or active trouble codes and that the check engine light is not on. Start the drive cycle from a cold start; preferably on a cold morning.
A. Start engine and idle for approximately 2 minutes and 10 seconds. The secondary air injection and EVAP leak detection tests are being conducted now.
B. Begin driving. Accelerate to 20-30 MPH and maintain steady speed for 3 minutes and 15 seconds. During this drive segment the ECU is checking closed-loop operation and oxygen sensor response time.
C. Accelerate to 40-60 MPH and maintain steady speed for 15 minutes. The catalyst monitor is being run now.
D Decelerate to a complete stop and idle while the engine is in gear for 5 minutes. The ECU is testing the system for EVAP leaks.
E. End of Drive Cycle
If readiness status of all monitors do not switch to “ready,” ensure preconditions are met, and complete a new drive cycle after the engine has cooled overnight. The BMW 3-Series drive cycle (drive trace) requires driving both highway and city speeds. If you feel you might be unable to complete the drive cycle safely, please seek assistance from a BMW repair center or smog check repair station.