GF 99 Impreza MAP only ECU reflashing

I have been looking and been unsuccessful in finding a way to reflash the stock ECU on this older car (99 impreza Outback Sport) If it used a Maf sensor there is a company that makes a Bluetooth OBDII connector and licenses so that you can reflash the stock ECU. However after talking with the the people at project lambda their software does not work with the limited Map only cars that were made like mine. There are plenty of good options for tuning 05+ Na imprezas or 02+ WRX's. I just wanted to know if there was some way to reflash the stock ECU in my car. Am I going to have to either get a WRX ECU with all the sensors and wiring to go with it or a stand alone ECU?

After looking further into it, it is not worth it trying to tune this particular stock ECU. So I am going to have to build an adapter harness from my loom to a Bugeye WRX ECU. I have to change a few things like crank trigger and convert to GM LS style coils but it doesn't look like it will be super difficult.

Sorry for the slow reply. In general terms it wasn't until 2000 onwards that the ECUs became reflashable, however I do recall there are a couple of options for the 99 model but I haven't used them myself. In all honesty I'd suggest you strongly consider a plug & play aftermarket ECU rather than retrofitting a later model ECU and the necessary hardware to you 99 model. There are plenty of plug & play options on the market for these cars from a number of ECU manufacturers which suit most budgets and requirements.