Best lowering springs for street

My buddy has those HR springs on his GT....i'll vouch for those too they look great. He's still using stock shocks/struts with non adjustable aftermarket control arms. It sits about the same as mine though with the Eibachs.
 
I don't mean to jack the tread but I just picked up some used "c" springs for 50 bucks. What are peoples opinions on these, and about how much do they drop the car? The exhaust I have hangs pretty low so just a small drop would be perfect.
 
Here are pics of the h&r sports. Picture #8 from the top and on are the pics with the stock rear control arms.

http://www.cardomian.com/ride/732323

Also, just as a side note, The car sits about a quarter of an inch lower on the driver side than the passenger side, but that's another issue i have yet to figure out :( It was this way with the stock springs and it carried over with the new setup.
 
I have a brand new Eibach pro kit for sale as well as a set of the "E-bay springs" . The e-bay springs will drop your car about 1.75 front , 1.5 rear . I will give you a great deal on either .


Pro-kit:

JOLWE-stang2011.jpg
 
Stupid question, but if lowering springs are installed do the shocks/struts have to be changed as well? If so, are their specific shocks/struts for cars that are lowered?
 
They don't have to be changed but I highly recommend it. the stock shocks are not suited for lowered applications. Some shocks work better with certain springs. However, if you go with something as high end as bilsteins they will be fine with just about anything. it all depends on what type of ride you are looking for.