Twin turbos? What? Why? What gave you the idea that two turbos was better than one? Hell, why not 6 superchagers? Maybe even 7!! I have some better advice. First off, ditch the entire wrx drivetrain, just strip it down fully, trans, diffs, driveshafts, etc. Next, find a good builder, your going to want to transplant a real engine and drivetrain into the scoob. I'm not sure what you can fit (size-wise, this is far from bolt in), maybe a blown v8 or something, a decent transmission, and most certainly, RWD. Hell, if they can do it with those hondas, they can do it with a subie. Of course, this would make the car pretty nose heavy, and it would handle like crap, but, if you really want the 1khp I guess you can live with that. Otherwise, hell, if you have the cash, you can probably get 1000hp out of a built 2.5l block, but it wouldn't last more than a few miles, but hey, you've got 1000hp. Unfortunately, HP is an almost meaningless indicator of real world performance. If you can't drive, you'll still get beat by cars with 1/10th the performance (I'm obviously not talking about drag here, although it still holds true to an extent).
jb