[Acree]

I've done considerable research into this topic. When you get passed all of the hardware and wiring requirements, this is the first step in what it's going to take to seamlessly integrate the two CANBUS networks.

You will need to reflash the stock FRS/BRZ ECU and change the CAN lookup table. Change CANID 0x141 to 0x142. Then, have your controller listen for 0x142, read the values, change what you need (such as putting the LS engine RPM from the LS PCM in the correct byte), and rebroadcast your modified byte string on 0x141.

This will make sure no other components are listening to the Suby ECU except your controller. Your controller will broadcast on 0x141 and fool the entire network.

Rinse and repeat for any other IDs you need.