Hi mate, have a read of the thread "how I fixed my knocking shocks"
https://www.scoobynet.com/suspension...pe-struts.html
Basically, you can disassemble yours and re-grease them, but this is a temporary solution unless you also fit grease nipples and re-pack them wit hgrease periodically. You can also get KYB Ultra SR shocks, or Excel G's, which should fit your car but you'll have to be careful and might need replacement top mounts which are quite hard to come by. Have a read of the thread and see what you come up with.
My solution wasn't the cheapest, but it should be a long term fix and I love the results - car hadnles beautifully now and still rides very comfortably.
Your car is an Sti - this causes some additional problems beciase I THINK the hub knuckles are different.... do some research and I'm sure you'll come up with a solution. Beware fitting coilovers. IMO nothing ruins a road car faster than cheap-end coilovers!