I have small experience it this matter (spent ages mesing around with different ride heights).
Basically you are OK to drop upto about 35mm on 17s you can go lower but if your springs aren't rock hard you'll find that the outer trailing edge of the tyre fouls the front rear (at the horizontal) arch. Happens on lock under load (eg. corner or bump).
With the stock 14s on hard spring you can go as low as 65mm (at the front). This makes the say very stable (especially at speed) but is otherwise pretty crap.
If you're repalcing the shocks and springs I'd go for one of the coil-over options with adjustable platforms. Then you can adjust it to your heart's content, if you get any rubbing.
Other coil-over advantages - you could get the car corner weight then set-up properly. You can (relatively) easily and cheaply get new springs if the supplied items are too hard/soft.
Look at whiteline's site and have a quick searching session here.
Good luck.
PS Spring compressors are bastards.