Z is right. I had an 08. Was planning to make it a really cool impreza but after thinking about it logically, and financially, it was actually considerably cheaper and easier to buy a turboed platform and play off that than to start with one that wasn't designed for it.
With the wrx, and the mods I put in to make it stage 2, it's still less than what I would have paid to make the impreza close to what the wrx is now.
I can still make it go more. With the impreza, I would have pretty much maxed out here. Plus with a car that modded out, it may not be the most reliable car. Lots of attention and care.
But that's just my 2 cents
Oh and you'd still need...
Spark plugs, injectors, fuel pump, tune, clutch, probably should do your heads, valves, springs, get the block checked and cleaned, and from that list, you'd be missing also rods, and crank unless I'm blind... Etc
Sent from my LT30a