i don't think he was referring to rear sway bar. chasis brace is a completely different mod.The F sport lower sway bar is 3mm thicker then the stock one that comes on the F (16mm stock vs 19mm with the F sport). Adding thickness to a sway will reduce body roll when turning in the F. Those that have this mod say it's worth the extra 3mm and it really reduces body, others question whether it really makes that big of a difference. It's up to you to see if it's worth paying for the 3 extra millimeters.
I found an interesting article that I posted below about how sway bars work (for those who aren't too sure), it's pretty cool stuff imo
i found a couple for IS350 which should fit the F( i think) i dont remember the manufacturer, a search on IS350 forum should yield something.Not to hijack this thread, but I'd like to find a really good STB for the F. I put one one on my last car, a G35 Coupe, and it really stiffened it up, tied the front end together. It turned the G into a slot car. I'd love to find something like this for the F.