Ok, just to make it clear.
You already have sti shocks and springs though you just want to lower it.
You are willing to give up ride comfort for road handling.
Are you able to get sway bars and the such strut bracing.
Imo, springs on their own will be a good fix for the meantime but inevitably be just a waste of money if you want to get adjustables in the end.
What is your budget for adjustables (if you were allowed them). It makes a big difference as there are other options available.
Are damper adjustables allowed? I.e not ride height?
An example could be Teins as they come lowered already as the shock body is larger hence the ability to damper slightly better but only are damper adjustable which can give you a firmer ride. (Scarce items though)
Or are they so picky you cant have any form of adjustable.
If you are keen, you could always go get the replacement Kyb setups which is OEM replacement but can be configured to your own requirements. (Shock shops can advise you of other brands that do it, i.e bilstein, tein)
None adjustable shocks but straight out of the box newer/stiffer/ etc then get corresponding springs to your liking fit to them.