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65mm (2.5") diameter
9k (502 in/lb) spring rate
Swift p/n Z65-178-090
Price is for a pair of springs
After reading many other positive reviews on both the GWR and Miata forums I finally decided to buy this product. My main concern for many months was whether or not I was up to the task of installing the header. But with the excellent instructions on Brian's forum as well as several Miata forum threads it turned out easier than I expected. After receiving notice that the header would arrive on a Friday afternoon, I began the disassembly process. After about 3 hours I had the stock manifold out. Later that afternoon the new catted header arrived right on schedule. And it is a thing of beauty. I opted for the stainless version. Installation on Saturday morning took another 3 hours, although I could have shaved some time off of that but I was actually enjoying the process of double checking torque values and cleaning up my engine compartment. I already have the GWR catted midpipe, so that connection was a snap. I put everything back together, reconnected my battery, and went for a drive. NO CODES! Nice throaty sound with my RSII muffler, and a significant boost in power and low/mid torque. Another happy camper here. I since have added a M-E tune and I feel I have realized all of the gains that Brian has achieved on his 2012 project Miata. I've put several hundred miles on my Miata since the install with zero problems. This is the car that Mazda should have built all along. Thanks Brian.
-- Ron P.
I red'all the parts in the order I placed and installed them in my car yesterday. I am beyond happy. The install went without a hitch. The results were fantastic. The new brakes track straight, make no noise, and stop the car authoritatively. The new rotors look pretty cool, which we all know isn't all that important, but having 6 women offer to bear your children, because your car looks SO cool is a good problem to have. Thank for great products and service.
-- Chaz C.