I agree with these guys. The wrx is nothing like your average tuner car like a civic or a 240sx. You need to be smart and prepare for problems because they will happen. My suggestion would be to find the weak points of your car like if it has a catted up pipe like the 02-03 wrx has and upgrade those first. You will get nothing but tickets and police harassment from a loud as catback. Without an up pipe and downpipe and a good tune, a catback is nothing but peacock feathers except instead of attracting pretty female birds, you just attract cops with hard ons.
If you plan on modifying this car, I would start with a stage 2 tune and the mods you need to support that tune. If it hasnt had the timing belt done and it has 100k miles or more, do that asap. If you want some guidance with this feel free to send me a message. I have a 2002 wrx wagon and even though Im 30 and this is my 10th or 11th car, I still went through all the sa,e things yourr about to go through. Please use a level head and caution. Be smart about your choices and practical too. Youve cbosen the wrx wagon as your first car, so I know youve got good sense.
This is great you guys are great.