well the stock springs are about 5 to 6 inches in diameter, and the GC springs are like 3 to 4 inches in diameter. the concern was the spring and strut pertuding into the trunk area, thus bottoming out the rear end. GC told me that i dont need the pillow that the stock springs have at the top. the silicone pillow provided was meant to be on the bottom where the spring and strut meet. so im confused.