Originally Posted by Re3iRtH
I will install the rear sway and chassis brace this week. I didn't order a front sway, because I
read (can't find the post off hand) that the F-sport front sway only adds 5% stiffness over stock,
and the rear sway adds something like 150% more..
When the F-Sport accessories package first came out, Lexus initially posted that the F-Sport front sway bar added 6%
stiffness over stock and the rear F-Sport sway bar added 151%
stiffness over stock.
Lexus later revised the IS350 % stiffness of the F-Sport sway bars stating that the front F-Sport sway bar now provides a 42.8%
stiffness improvement over stock while the rear F-sport sway bar remains the same at 151%
The change in the % stiffness has been a topic of discussion on CL for years as it is unknown whether or not the revision to the % stiffness change for the front was intentional (meaning the original statistics were incorrect) or not. It doesn't help that the IS250 and IS350 both have different % stiffness increases when the consensus here is that the OEM sway bars for both models are the same.
Those that did the rear sway bar mod first and then the front sway bar mod later down the road have all said that the F-Sport front sway bar has a noticeable improvement at improving initial turn-in and reducing body roll in the front but the F-Sport rear sway bar mod has a much more noticeable change to the vehicle dynamics.
As an owner that had previously driven with only the F-Sport rear sway bar for nearly a year and a half prior to finally getting the F-Sport front sway bar, I sincerely believe that the revision to the % stiffness over the front stock sway bar is more accurate at 42.8%
as the oversteering issues that I previously had with using only the rear sway bar were now gone when the front sway bar was later installed, specifically at certain on-ramps and corners which I would use to analyze the car's handling characteristics. I noticed that the body roll that I used to have up in the front was greatly reduced and I'm fairly certain a 6% increase over stock wouldn't have a noticeable impact if that old statistic was still used and was accurate (The old 6% stiffness data is why forum members here continue to skip the purchase of the F-Sport front sway bar due to the belief that it has little to no improvement over stock [which is why I'm typing this long email response for added perspective]).
This previous thread may help provide an additional perspective to the whole F-Sport Front vs Rear Sway bar discussion: http://www.clublexus.com/forums/susp...-sway-bar.html
Hope this info helps.
Originally Posted by azfsprt
In addition I would recommend getting a LSD from an FR-S to get you the best handling ability to come even close to the s2000.
Unfortunately, the FR-S Torsen LSD is only compatible with the IS250 and not the IS350. When it comes to IS350 differential options, we only have a handful of vendors to choose from and most available LSDs are pricey (I definitely know this). >_<