As with many aftermarket offerings for the NSX, they are mostly expensive and compromised. We have elected to not use the internal throttle position sensor in the throttle motor, instead using a Variohm TPS on each bank of the intake to generate a throttle position signal. Fundamentally, you want the ECU to know the position of the throttle blades, not the position of the motor driving them. Spoon famously developed and raced an ITB-equipped NSX in period, and had helpfully solved my problem all those years ago. Undoubtedly, this part has been through a few different cars before ending up in Project NSX.