Full long block replacement, who has done it themselves?
 

I'm curious as to who has changed/replaced their entire engine themselves. What is required ECU wise to get the new motor in? Is it as simple as removing the old motor, swapping the ECU onto the new motor, fluids and wires, and firing it up?

You don't swap the ECU per say as that is mounted in the car. You will disconnect the wiring harness from everything and move it out of the way and then remove the motor and then reinstall the motor and hook all the connectors back up. Hopefully you can just move the A/C compressor out of the way enough to not have to crack open the lines. I would remove the front bumper, cooling fans, radiator, and radiator support to give you room to get the motor out the top. I would leave the tranny in place. Be very careful with the coil packs and anything else that can get damaged by hitting the frame rails when you pull and reinstall the motor. I haven't done an FA20, but I have been part of multiple EJ motor pulls.

I am not sure about this car, but with other boxer LB swaps there are a couple of important steps other than just swapping it.

There could be crank endplay checks and shims required to install.
And if the flywheel bolts are of a certain type, then you need to replace them.
Sounds like you need the real factory manual.
Not sure if the one we have available goes into all of those details.

I did it in my buddies driveway without air tools in 7hrs

The Frozen North

It might be possible, but there isn't much hose to work with to pull the compressor out of the way. Having the luxury of working in a dealer I always just recover/recharge.

No need for this, there is plenty of room to move the engine forward if you remove the exhaust manifold, which shouldn't be too hard even on jack stands.

I'm pretty sure that flywheel bolts are plastic region bolts and will need replaced. I've never ran into any flywheel bolts that weren't.

I read the manual. It actually does go into enough detail to do this yourself.

There is no endplay meas. mentioned, just bolt & go.

I have done this on a bunch of Subarus and it is generally just bolt and go. Sometimes to do a clutch I would pull the engine if there was no lift, took about 45 minutes. Took about an hour or so o put back in since the coolant had to be put back in.

Neither flywheel nor pressure plate bolts are tagged as one time use in the service manual.

I can confirm they are metal bolts. I did replace them with ARP flywheel bolts.

Removing a motor does require to pull the gearbox or can that be left in place?

The transmission can be left in place, but you just need something to support the front portion of the transmission.

In most cars, I would pull the engine with the trans. But in this car the trans is so easy to remove, it probably makes little difference either way. Once you get the airbox out of the way, there is a ton of room, too, so the radiator and fans can probably be left in place.

Probably the most annoying part of the swap in these cars would be pulling and reinstalling all coolant/fuel hoses and electrical harness.

If the pressure plate/clutch cover bolts have lock washers they are one time use. Just a rule of thumb used by most. I find it hard to believe the flywheel bolts aren't plastic region but Subaru is unique in many ways.

Yeah, I was a bit surprised to find that not only are head bolts not single use, but there are also no maximum stretch measurements. I worked on Honda/Acura for 10 years before moving to Subaru, and the early head bolts are one time only while the later design have a thickness spec.