Sway Bar Upgrade

[Adam]

I'm interested in sway bar upgrade for better handling.
Any recommendations for 1999 Lexus GS400 ?

See "Sway Bar Upgrade" here...
https://www.clublexus.com/how-tos/a/lexus-is-gs-performance-
modifications-363369
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Sway Bar Upgrade

The sway bar is what holds the suspension to the wheels and controls how
much "roll" your chassis gives when you make a turn, especially a sharp
turn. A very popular upgrade is the F-Bar upgrade that is much stiffer
than the stock sway bar. There's at least a 50% stiffer setting for this
F-Sport sway bar and it really shows. Your ride will be much more
responsive with much less under-steer going into a sharp turn. You won't
slide in your seat as much. This makes the car feel much sportier, and
although it will not increase your horses, it will allow for a higher
speed into the turns. For less than an hour's time with install, this is
a modification well worth your time and effort.

[Davoud]

...You won't slide in your seat as much...

Nonsense. Neither sway bars nor anything else can nullify Newtonian
mechanics, particularly as applies to momentum.

If you want to avoid sliding in your seat, spend $ a few thousand on
some Recaro seats. Never mind they might cost more than a 19-year-old
GS400 is worth.