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Spring rate: 12kg (670 lb/in)
Inner diameter: 2.75" Length: 7"
Swift part # Z70-178-120
Roadstersport II was a great purchase, easy install, and sounds great.
I received the Roadstersport II, and I wanted to compliment you guys on an awesome product. The Miata should have these on from the factory. They make a great sound, that is not obnoxious at all. The exhaust also installed seamlessly!!! I will buy all of my Miata stuff from you in the future. Thanks,