We have the HYPERMAX III on our 370z.
Great for everyday driving. Ride quality is not at all compromised. If you set the dampening to the softer side, it actually rides smoother than the stock shock and spring set up.
Ride adjustments on both springs and shocks makes it very tunable for any weekend track warrior. It also comes with top mounts, 36 way dampening adjustability.
We didn't try going past the number 26 out of 36 to see if stiffening the dampening would improve the handling of the car.
If your looking for more daily driving set up, this is it.
As for the KW Variant 3, nothing but good reviews so far, but then again, thats from our G37 customer base. The progressive design on their springs makes it ideal for daily driving. 14 level adjustments for the dampening should be plenty tunable for street or track. Great stainless steel quality build on the shocks.
HEIGHT can only be adjusted via the spring purch, NO height adjustments on the shock side, meaning you can't adjust the spring compression.
The only thing thats missing IMHO is the fact that you have to use your OE top mounts. For the price, they should have provided that.
If your looking for quality build, great street performance/weekend track, go with the KW'S
My personal favorite so far are the JIC magic FLT TAR series. Similar set up as the HKS HYPERMAX III but the JIC'S are only 15 level adjustable for dampening. Also comes with top mounts and height adjustment is recommended to be adjusted on both the springs and the shocks. Best part of this setup is that if ever anything goes wrong, they re valve inhouse. Even after the warranty expires and you want to get the shocks/struts re valved, you don't don't have to wait months to get them back to new or you can request for them to adjust the gas levels if you want them stiffer or softer. They can also build you a race setup if need be. The first JIC track set up the owner build on a 370z did 1.45 at laguna seca last weekend. That car was completely stock aside from the coilovers.
Best part is that they are only 4 miles away from me
So any warranty issue's or any custom build request ordered from us can has a very fast turn around
Unfortunately, JIC'S won't be ready for another 2 months
HOPE THAT HELPS