I have a 98 forester and I want to put a set of stock 07 Impreza 2.5i springs in it. Will they fit and will it lower my Forester at all?

there's a couple really good "will this suspension fit my car threads" - i would suggest looking at it for forester and impreza mix-and-matching.

 

you could also find the spring rates, diameter, and length you want and order from Eibach.  i just did that two days ago. it was pretty handy.  i sifted the internet reading various experiences and dialed in the height (i wanted it more "lifted" than lowered" and spring rates - a little more than stock but not much due to rough roads locally.