Specs tell a different story. I have worked hard since 2003 to provide owners with real world specs so they can avoid making mistakes that make their car less then it could be. Nothing about the Spec R spring for the Z stands out vs other simular choices. Best performance spring for the Z remains the Tein S-tech. I would also mention the Cobb spring but it has been discontinued and I don't care for of how high that springs rear rates are. (Nissan Motorsports T2 spring is out because of specific shock requirements) Everything else is a compromise on performace with wide progressive rate spreads or compromises dependent on what oem shock was on the developement car. Exactly why I imagineered my own springs for Koni shocks. The right spring didn't exist so I made it exist.


Swift 350Z Spec-R progressive springs 1.2”/1”
Spring rates in LBS initial/final Front: 291/392 Rear: 280/448

Eibach 350Z Pro-Kit progressive springs 1”/1”
Spring rates in LBS initial/final front 296/384 initial/final rear 316/421

^ Notice that the two springs are almost a copy of one another. Notice the review below.

 

^ what is the shock needed for Nissan Motorsports T2 spring?

 

Koni 8242 DA shocks are valved for this application. You can also get Penske, Moton or JRZ shocks valved as well.

 

Interesting, as similar as they look on paper I would never categorize the Swift Spec R's as having excessive body roll. That's one thing I always felt was the Spec R's strong point. They were well mannered on the street and handled track use (and body roll) very well. I also thought the "progressive" tag on them was more of a marketing ploy, they felt and reacted very linear.. but this is not to so they are linear, they just don't work like any progessive spring I have ever felt.

 

OP! Update please, gives us some feedback on what you went with! I have some on the way and am thinking of keeping them and gettin D-spec shocks based on what ive read so far. I ordered camber arms as well as toe arms because i was planning on eventually going true style stance coilovers. But ill wait and see how they feel.

 

Installed them 2 days ago and so far so good. Definitely less body roll. I don't have any experience with other springs so I'm not able to give a comparison other than with stock. At my current height, with spring mount cut half an inch, I'm really considering just buying Tokico D shocks and considering myself finished with suspension. It's my DD and I ride it pretty hard so any lower and i'll have serious rubbing issues. I still have a bit of rubbing and it's mainly due to my wheel and tire size. I have my fenders rolled in the rear, and in the front I had to remove a screw holding the fender liner. Practically no rubbing now, except for on hard turns that involve a dip. I run 19x10 19x11 +14 all around.