Trying to decide which way to go with her so I need a little feedback. Soon she will be torn down to nothing for a complete repainting/restoration and during this process I would like to swap in a new powerplant. She's going to be heavier and I don't believe the ej25, with 230k miles, is up to the task. Problem is I love NA. I have an 04 WRX and don't get me wrong I love the power, but I hate the lag. All in I would appreciate what the expected cost and practicality of a few different ideas is:
Rebuild the ej25 with higher compression heads, racing flywheel/crank/pistons/connecting rods/cam and get the most out of the 2.5 while keeping her NA.
Find a totaled STI and swap in the powerplant/wiring harness/drivetrain/transmission/suspension
The last option is likely the most labor intensive, which I don't mind, so long as it's doable. I've read around and found some have the EG33 swap completed with great results but it is heavier and more difficult to fit into the engine bay. The EZ36 would be a dream swap for me. Power, torque, NA. I have read that some have attempted this swap and have had issues working around the immobilizer and limp home functions as well as no ecu capable of running the AVCS. Have any aftermarket ECUs finally been able to capture this function? Would swapping in the harness from a 3.6r outback be possible to retain the AVCS? I also don't know how I feel about drive by wire throttle as I prefer the direct response and control of a cable. I would love to build a chopped down and simplified EZ36 that retains the AVCS, perhaps with a manual control of its cam position.