Why an 03 wagon compared to a 05 or an 07? Reason I ask is are you looking for the looks or the cheapest price?
If anything like wrxtreme said go stock. With a wrx, most people that buy them want them to mod and to absolutly rape them. If you get luckly like i did, you will get a 2005 wrx with 30,000 miles. The previous owner was a 35 year old bachelor. He ended up trading the rex in for a honda accord. Dude was a beach nut and didnt mod the car 1 bit.