As it sits, HEADERS AND EXHAUST should be on the top of your priority list. I realize they may not make headers for your car, but custom ones can be made by you or a shop. You can get a kit with flanges and bends to get you started. Through in some good merge collectors and dual 3" exhaust and you'll see some serious power increase.
Just remember air can only come in as fast as it goes out. Also, a strong clean exhaust pulse can really draw in a lot of extra air through the intake.
There's a lot of things you can do to your car to get you some power but your engine is already being choked by the exhaust.