I Installed the black spring when I resealed my fuel bowl. Idle quality is up, throttle response is up. You'll really notice a difference when you lay the hammer down on a hot tune. It's also super easy to burn up pumps if you don't use these wisely. If you're looking at this kit to cure low fuel pressure, don't do it.

So nice to find quality parts, thanks guys for keeping me away from eBay junk and the price is better to boot.