These black springs are mine and i thought they were stock. They came out of my 1988 pontiac firebird 305. My front springs were iroc/ws6 and i also have the 24/36 sway bars.

Here is a pic of it next to a stock spring (with 1/2 coil cut) from a 1990 pontiac firebird 350



Which springs are more desirable. i use this car as a street/strip car as it does a 12s 1/4 mile. i can paint either one to look nice.

 

The one that is not red is a progressive spring. Both are stock, the red one would be better