I was think of either throwing on a petit ecu unlimited and a profec II and a walbro to run around 14psi. But would it be alright to just throw on a walbro and a profec and run around 12psi? Would it hit fuel cut? thanks

 

Fuel cut occurs at 12.1 psi according to the Mazda Service Highlights manual. Also the RX-7 uses a "MAP" (Manifold Absolute Pressure) sensor instead of a "MAF" (Mass Airflow) sensor. A MAF sensor corrects for the increase in air supply to the engine, but a MAP sensor does not, so you need to have an aftermarket ECU in order to correct for the fuel supply needed to support the extra boost. For the money that you would spend on the Petit ECU, you're better off to buy the PowerFC and have a completely tunable unit.