I'm in New York, only California has tougher emission testing, lol. I have a 2002 wrx with a 2003 ej207 swap, twin scroll turbo, Tomei catless down pipe runing on a jdm ecu. My car did pass inspection recently but had to install the usdm ecu for for the state inspection computer to be able to communicate with my car. The inspection computer would not communicate with the Jdm ecu. You will have to deactivate all the tgv related diagnostics on the usdm ecu in order to not have a check engine light. You will want to unplug the avcs when runing the car with the usdm ecu. Ideally you also want to tune the usdm ecu to work properly with the 565 injectors on the ej207. Once a year I'll have to install the usdm ecu in order to pass inspection.
Ecu work done with open source.