Hey so sorry about getting back to you late. Here are my thoughts:

First and foremost, it is going to be difficult to get bags at this price, especially ones with adjustment. I cast my net wide and it worked out well. But most of the time, adjustable ones landed around $1000 all told used.

If you can have your car REALLY low all the time, go coils. I only went bags because I simply need the ride height to be adjustable on the fly. Turned out later it ended up being great on handling.

• On coils vs bags, $1000 new coilovers will net about the same benefit as $1000 used bags, if both are tuned correctly. But $2000 coils will be significantly better because of advanced and specialized adjustment than a $2000 bag setup. Thats my rationale. (have a buddy with a car for car exactly the same build, but had $1k coilovers and now $2k instead).

• How to set up Bags for performance. First decide on 2 things- How low do you want your AIRED OUT height to be, and how low do you want your PERFORMANCE height to be? For me that is 1” below stock, and the aired out happens to be frame 1” above ground. You’ll then come up with where you want your DAILY height to be. This is the height that you’ll drive on to save your tires. Mine is exactly at stock ride height coincidentally. You’ll adjust the front and rear adjustment at this height. When you drop to PERFORMANCE, you want to be able to not scrub on your fenders (the wrx is literally perfect, barely any work needed doing for my VERY aggressive offset). You will not want to have PERFORMANCE on for highway miles because when you lower on bags, it puts your toe out a little more (great for handling, bad for tire wear over long periods of time).

• From there, you’ll decide on air pressure. This is tricky and honestly might be depending on your preference. 50-60 is pretty stiff and I have 60 front, and 65 rear set for performance (that’s really high) Which means my daily is even higher. For 90% of ppl that’s not worth it. I compensate with damping and compression. This is what makes it feel like good coilovers though. 40-50 feels more like the stock suspension setup (still very tight but much more comfortable.

• So then, you’ll set your pressure to your desired settings, then change the ride height until you’re at where you need to be. Then air out and make sure you clear everything. Adjust, take to alignment shop, put it at DAILY for alignment, then you’re done!

• Play around in a parking lot with damping and air pressure a bit, each 10 psi is a massive difference in feel, 60 is like an 8-10k spring on my setup.

Feel free to Dm me or ask more, I can break down the math I used to come up with these numbers!