I have a 2005 6m sedan. Looking to lower it. What is better the Eibach pro kit or the 350z springs. If the 350z springs, what year? Does it matter? Thanks! Also how much better will it handle if I replaced the sways at the same time, will it make that much of a difference? Thanks again!!!

 

350Z springs.

Why.

Pro-kits are progressive and you have to get past the softer initial rates to begin to experience the higher final rates, which aren't that much different then oem. This will mean more weight transfer issues that will be felt in the form of greater brake dive, more squat as you roll in and out of the throttle and a less lively fell over all.

Eibach G35 Sedan 1.1”/1.1”
Spring rates in LBS initial/final front 259/334 initial/final rear 359/416
The sedan Pro-Kits were developed on a non sport sedan, they did not use a sport suspended car to do the R&D work.


2003/2004 oem 350Z springs linear (known as unrevised springs)
314/342

2004.5-2007 oem 350Z springs linear (known as revised springs)
314/427

While it would seam that the revised springs would be the one to go with, your oem sport shocks don't have the extra dampning power to deal effectively with 25% stiffer rear springs. Your better off with the unrevised springs. Dynamically driving both back to back the 342lbs rears at first won't feel as lively. But you'll have more traction exiting corner's and the throttle is more forgiving when you start to tip in as cornerning levels begin to ease.

If you want to, their is a way to run a Koni setup that has a 1.1"/1" drop with 560/427lbs spring rates, though it would cost about $1170 . Which is a setup I ran for awhile and really liked, just wasn't low enough for me.