For Ford Mustang 2005 to 2009. Every spring produced by H&R comes from the H&R ISO 9001 certified engineering and manufacturing facility in Germany. All H&R springs are produced from a special 54SiCr6 spring steel, which has strength rated at 290,000 psi resulting in unrivaled tensile strength and resiliency.For some, the idea of upgrading a vehicle with performance suspension sounds appealing, but a noticeably lower ride height and slightly firmer spring rates don't. H&R OE Sport Springs are the solution. OE Sport Springs lower the vehicle subtly, yielding a slicker, more aggressive stance without noticeably altering appearance. The end result is a car that is more controlled and balanced, yet has the uncompromised ride characteristics you're accustomed to.