Review on Holley 20-13 Secondary Diaphragm Spring 🔧 Kit: Maximum Performance Upgrade for Reliable Engine Efficiency by Boss Spangler

This is definitely not a Holley product. I have some more Holley springs to compare and there is a difference. The coils don't match, but that doesn't mean the spring rate isn't the same, the two uncompressed springs seemed to have the same spring rate when compressed, but that just feels. I love that some of them are fully painted instead of just on top like the original Holley springs. The colors seem to be quite distinct.