Girlfriends brother just bought one.
Let me tell you what I have gone through with this thing.
This thing is very very slow, going up a hill it doesn't go past 35, it shifts into 2nd at 2700rpm, and into 3rd even lower. It is perfectly smooth, like it's just a low powered engine. No sputtering, no hesitation, it just feels like it's only got like 50-75hp - the car supposedly only weighs 2000lb. Failed smog test. Smog test dude said it was a clogged cat that is causing the power loss and the failed test.
I removed the back cat, still no power. Removed the Y-pipe from the manifolds along with the front cat, still no power. So I don't think it's a clogged cat.
I retarded the timing some (turned the distributor), no power gain. Advancing the timing only caused detonation, so the timing is set correctly at the distributor.
Even though it's smooth power, I decided to look at the carb. Dinky little two barrel, the back barrel appears to be a vacuum secondary. With the car in park, I floored it and made the front barrel open all the way up, the rear barrel only likes to open about 20 degrees max instead of the full 90 degree open position. I don't know if this is the cause or not. Also, there is only one choke looking type butterfly on the top - in the front barrel. In the back barrel there are threaded screw holes with nothing in them, maybe something is missing - do you know? I have no idea what this carb (and the entire engine is supposed to look like).
Beyond that, I have no idea what to look at on this car. If it was a Ford, I would check to see that the timing belt was put on properly, but I don't have a Subaru book, nor do I know how to adjust the timing there with the belt, or if it even needs it on this car.