Review: HKS Hipermax IV SP for 370Z

ShinyaPGH

If you have 12k/11k swifts on OEM shocks, these SP coils will actually ride better on the streets. I know many people love KW v3's, but they still come with progressive 8-9k springs in the rear, and these HKS coils will probably outperform them on the track. KW v3 probably will ride a tad smoother on the streets though. (that's the nature of the progressive springs anyway.) But just comparing to all the coils out there under $2000, I'd rank these HKS Hipermax IV SP at the very top imho.

On the spring rate, it does seem unusual. But just from watching so many of the HotVersion and Best Motoring videos on Youtube, Japanese race drivers who test for these JDM tuners typically HATE understeer. And having such high spring rate in the rear ensures the car will not understeer on corner exits. Higher spring rate with better damping seem to work better for our heavy Z34 cars. The car has more tendencies to oversteer on mid turn and exits now, and I've been able to dial them out with adjusting compression and sway bars.

Another thing I noticed from this setup change, is that Toyo Proxes R888 are better match to these SP coils than S-04. S-04 has a hard time gripping with such stiff suspension. S-04 felt better on the GT coils with softer springs. I didn't realize tires can feel so different with different coilovers.