After reading this great writeup, I am planning to do the same thing either when I install rear MeisterR coil overs or when I install a Magnaflow cat-back exhaust, depending on when the bar arrives from Japan.

Based on Pnuge88's info and other guides, this is what I already ordered:
1. "Toyota 48812-30400 Bar, stabilizer, rear Genuine OEM Part" (via eBay from a seller in Japan, about $105 plus tax with free shipping)
2. One pair of Figs 17mm bushings, "GEN1 IS300 SXE10/GEN2 GS REAR SWAY BAR POLYURETHANE BUSHING" (about $45 with shipping)

This is what I haven't ordered yet and have questions about:
3. Pnuge88 used a pair of Mevotech Supreme MS86836 Rear Stabilizer Bar End Links ($60 for a pair, plus tax and shipping)

I am not planning to slam the SC430 to the ground, stagger the wheels, or put huge rims on it. I was originally planning to lower the car maybe half an inch at the most when I put the coil overs on. The stock 2006 suspension is pretty sloppy, so it may already be a little lower than when it rolled off the line in Japan. The Mevotech end links (#3) look a lot beefier than the stock SC430 and IS end links. There seems to be conflicting information about whether the IS end links are required or not and if so, whether the ride height or the sway bar bolt hole diameters (or both) are the determining factor. I also plan to order the parts for the front sway bar swap. I want to make sure the car rests on the front and rear suspension at equal heights without having to adjust the front and rear coil overs to make up for something I screwed up with the sway bar setups.

For the rear sway bar setup, assuming I replace the rear sway bar end links will I have to lower the car a full inch to keep the new links from breaking?
If I try to keep the stock links and height, are the bolt hole diameters going to work out?

I'd love to hear from people who've already been through this same dilemma and have firsthand experience.

Thanks!