Welcome Dom!Please bookmark this page:
http://forums.altimas.org/Start from there in the future and you will find all the info you need... i move threads to their correct area so when you are looking for a "springs" question you know right where to look!
This is 2 seperate questions that you could have found the "general consensus" by browsing around a bit in the performance, and then the suspension area.
Fujita is the best bang for the buck, and eibachs are the most widely used by us.