I would't lower my car on springs only without testing the ride first. I have had 2 cars lowered on springs only and the ride was terrible (PI springs on an Ibiza GTI and an Impreza on Jamex springs). My brother had a Nova lowered on Spax springs and it was awful as well.
Many people on here rave about H&R and Eibach springs but I'm still not convinced the ride will be any good lowered on springs alone. I'm welcome to be proved wrong if anyone in Leeds has a GTI lowered springs only and wants to take me for a drive though.
Don't get springs without testing the ride first is my opinion and don't listen to people saying 'it will be fine' either as what is fine to some may not be to you! A lot of people who lower their car won't admit to the ride being ruined because they're trying to kid themselves into believing they didn't make a big mistake! I have no problem admitting when I mod I have made was bad, but I am in the minority.