Hey SAF, lightweight is 154, so you really only have to lose about 8-10lbs. I just competed as a lightweight and I was fluctuating b/w 158-162 the last week of the show. I weighed in at exactly 150 after losing water on friday before the weigh-in friday night (1 40mg lasix in am & 1 25mg Hctz at noon).
BUT, if you are already ripped to fuck like everyone is saying, then you may not be able to get down to 154 without sacrificing muscle, so unlike what someone already said, just getting down to 150 will not make you look "SICK", it will make you look worse if you lose too much muscle. I would suggest just keeping your diet steady all the way in (actually probably increase carbs to about 150/dy), take your diuretics on the friday, and see wher you weigh in. By the way, keep your water as high as you can until you start the diuretics, then just sip (not even 1 500ml bottle from then until stage time).