I tried searching and couldn't find much. anyways, I'm 99% sure on this, Sohfast.com thinks that when putting a 99 Si Sway on, you need the bar w/ hardware (endlinks, dbrackets), LCAs, but NOT the Dampening forks.
i'm almost certain you need the forks, please verify if i need them or not. Also what's a good deal all together for all these parts??

Eddie

 

you will need the dampening forks. Going rate for this stuff is around 350

 

Yes, the forks are a must because the Si forks are wider than your stock ones. I did this swap about a month ago, but because I traded all parts with an Si owner who wanted more oversteer, I didn't end up paying anything at all. I would hit up junkyards to try and get this stuff, $350 sounds pretty steep to me - you could probably get a front and rear set of aftermarket ones for about that much.

 

s/t makes one for the front w/all hardware for $120.

 

As stated above YES you will need the "Si" forks and lower fork <u>bolts</u>.

I swapped out my DX hatch stuff for Si stuff and didn't have time to install the front Si swaybar... but after talking with other people... they said I don't even need the front Si swaybar... I'm undecided still and would like to try it with the Si sway since I do have all the front Si parts on the car!