I just got my Stillen sway bars installed and I'm really surprised how much of a difference they make. I though the car handled really well but the bars make a huge difference especially with agressive driving (eg take it on the track/course). This is an excellent bang for the buck suspension upgrade and I highly recomend it if you push the car at all.
I assumed that the bars would come with bushings so I called Stillen to inquire. They recomend using the stock bushings unless the car is being tracked, etc. Energy Susepension doesn't make a bushing set for the 370Z that I could find but there is a universal greaseable bushing that should fit the Stillen sway bars if you need that little bit of extra resistance that the urethane gives you.
They are $16 a set at Summit... in red of course
Energy Suspension 9-5161R - Energy Suspension Greasable Sway Bar Bushings - Overview - SummitRacing.com
Energy Suspension 9-5159R - Energy Suspension Greasable Sway Bar Bushings - Overview - SummitRacing.com