1.6T Ferrera Dual Valve Springs G4FJ kona All H&R products are crafted

All H&R products are crafted in Germany and exceed ISO 9001 quality assurance standards

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GFB’s DV+ solution on the other hand is more responsive

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1.6T Ferrera Dual Valve Springs G4FJ kona All H&R products are craftedSPECIAL ORDER SET OF 16 Made to rev safely to 10,000RPM Made in the USA Ferrera double valve springs are the highest quality available, needed for 7,000RPM or up to 10,000RPM. Harmonics or high frequency fatigue is present in all racing engines and will usually destroy the valvetrain if not controlled. Properly designed valve springs will control the dominant harmonics, provide the needed stability, and reduce valvetrain component wear. Ferrea valve