SS Springs

ss springs' claim to fame is that they have more bias in the passenger side spring to make the car launch straighter, since the car tends to roll toward the passenger side
some people don't like that they make the car sit lopsided in the back, and others don't notice it or don't care

their original intention back in the day was for Super Stock drag cars, but with the suspension technology advancements are now out of date, and most people use them for hot street/mild drag applications...or resto drag cars
i personally don't think they're necessary til you get into the 11s in the 1/4 mile...granted, they may help slower cars launch better, but i have not seen any direct comparison to prove that they are a huge difference....i'm leery about buying some because i think all they'll do for me is raise the rear of the car and i don't need that....

if you have a high horsepower car, consider caltracs with monoleafs....
if it's not a drag car, you may consider XHD springs from mancini...they supposedly provide about 1" lift in the rear over stock...