on swapping out the boxer 4 for the boxer 4 found on the wrx

Probably quite a lot. Due to the torque of the wrx engine. You would need engine/gearbox/drive shafts/engine mounts/custom exhaust/wiring loom. virtually everything underneath the body! Should have just bought a WRX mate lol Would have been easier and cheaper!

you best bet would be to turbo your 2.5i. A lot of people do that and it's not as hard as swapping the engine.

holy crap talk about opening up a can of worms! that would be the hardest motor to swap over you would be better off just turboing your saab save you time and a lot of money.

upgrading the engine from the linear to the aero (wrx) will be expensive and not worth it , it would be much cheaper to sell your car and buy an aero. to do the swap you will need at least long block ( the entire engine), all electrical, ECU, gauge cluster, hood ( unless you go front mount) , exhaust. Maybe next car :)

the two cars are exactly the same.The saab flat four is the same as the subaru flat four, that is the whole purpose of the car. theres no need to swap out the motor. If you are linear just go turbo thats all you need to do especially if you have a 2.5, you will make very good power, tq and hp.

The 9-2x engine is the same model as the wrx with a major exception, the 9-2x is open deck and not built for boost. it is a DIRECT swap, I would not boost the 9-2 linear as the engine wasn’t built to be, plus all the additional things you’ll have to get (ecu, injectors, aftermarket turbo components, etc etc) while thr factory boosted engine already has this. the 4eat is the exact same transmission used in other subarus even the 6cyl ones. some wrx’s have a manual but the 4eat should be fine the 9-2 has thr sti steering rack the drivetrain may lack lsd components but that’s it so the transmission and drivetrain aren’t the weak points.