I have an '07 Forester FXT with 5 speed manual. Previous owner bought it new and documented every change he made to it in a build thread on the Forester Forum. When I offered to buy it he had a WRX turbo in it and that took the HP up to 355 on the dyno. I forget the torque numbers but those were incredibly high as well. I had the option of buying the bigger turbo with the exhaust pipes and intercooler associated with it, but I didn't want to remove it all every two years and re-map everything for emissions testing. So he put the stock turbo back on it, along with the stock exhaust. Even the stock turbo setup has 224 hp, and the torque is about the same number at 3,000 rpm. Impressive little engines. The suspension, he left on the swift springs which lowered it a couple inches, and he also left on the STI sway bars and STI rack and pinion and front strut tower brace. It's a badass car! Handles like a cat on sandpaper. I have heard and read these cars are incedible off road. He also sent the stock suspension with the car. I have been tempted to raise it like you want to raise yours, but I have a jeep and trucks that can go off road, so that hasn't happened yet.
Looks like you got a solid car to build. Looking forward to seeing the progress. I'd suggest the Outback forum and other Subaru forums for off road upgrades. The choices are numerous. Raise it with spacers, raise it with springs, with sway bars, without sway bars. Skid plates are a must since the under carriage is so low, but everything is tucked up which helps. Speaking of skids plates, I need to locate one for mine, the plastic cover is nice but doesn't provide any protection if something is encountered on the road.
I would recommend changing the coolant first thing, and verify the hoses are good. The coolant needs a conditioner for the aluminum block and heads. And hopefully the PO had the head gaskets replaced. The older engines are notorious for blowing head gaskets from what I've read.
You might consider pulling the axles and replacing the boots and the grease inside them. If you do, just make sure you mark them well so everything stays balanced and tuned. If nothing else inspect them. I had an '05 Legacy Outback and the engine-side axle boots were extremely close the cats and in stop and go traffic they will burn up and fail. I've never seen under an Impreza Outback of your year.
That's all I can think of right now.
