https://rennlist.com/forums/parts-marketplace/777082-champion-motorsports-997-turbo-lowering-springs.html
This set of springs on Rennlist says they lower 1" to 1.2". They're for a turbo and have the H&R on them. It looks like H&R now owns Champion??
Typical lowering springs are 1-1.2" lower. The spring rate you request is not like a coil over adjustable spring. These springs are progressive in nature and are slightly stiffer than stock. They're $500 dollar springs, not high end race stuff.