BMW states that the CRT shaved 150 lbs off the E90 M3 just by swapping to CF in the seats and hood. That seems hard to reconcile with just a 30 lbs or so saving on the seats when they also state a 50% weight reduction with the CF hood. That would make the standard alu hood ( 150 - 30 ) x 2 = 240 lbs. Sounds heavy.
Note: According to this guy the alu hood is 22.8 lbs
http://www.m3post.com/forums/showthread.php?t=580764
This would make the savings from the seats 150 - ( 22.8 / 2 ) lbs = 138.6 lbs. With that in mind 50 lbs sounds rather modest.