For your 97 STS struts at Rock Auto are about $1600 for all four corners.
If you can afford this then I would go OEM for the ride is much better.
You may regret going with passive.
BTW I got all four OEM struts for my 96 STS a while back for $1200 from my local AC Delco parts house.
I will change out my original shocks when I hit 200k which I'm coming up on soon.