You can certainly set your car up to switch between stock ECU and MS ECU. I got spare connectors from a junkyard for the fuel injector harness, coil pack, and IAC. I also used GM weatherpack connectors to switch control of A/C, sensor power, and alternator. That let me switch back to stock for emissions testing or just part of the system if troubleshooting. I was going to say that I would be scared to buy a used MegaSquirt. You could spend months trying to decide if your problem is hardware, software, or tuning. I thought better of it after realizing that I took the same risk in building my own MegaSquirt. One bad solder joint, bad firmware update, or wrong data entry and I could have been chasing my tail. Jump in the pit and be ready to claw your way out.


Corbin
'97 GSX dressed like a '95 ESi