You want F-Sport PN PTR02-53080. It's the prior set, that includes only the rear bar for the IS250 AWD. I have it on my F, and it corners a little flatter, and rides slightly harsher. The stock ISF rear bar is 17mm and the F-Sport is 19mm. It's an easy bolt on, and I recommend it.
Oh, the thread you were looking for is here:
http://www.lexusfforum.com/forums/showthread.php?t=1630
Lou
Oh, the thread you were looking for is here:
http://www.lexusfforum.com/forums/showthread.php?t=1630
Lou