Just had contact with Seibon Carbon and as it seems it's not really worth the effort to change the stock hood with a Seibon hood.
The trunk lids is ok for the price as the trunk lid is "just" $880 which is cheap compared to others.
Stock (Steel): 10.625 kg (23.40 lbs) (OC weighed his at 26.0 lbs)
Seibon trunk lid (part: TL0708BMWE922D-C): 16lbs
Stock (Al): 10.20 kg (22.47 lbs)
Seibon hood (part: HD0708BMWE92M3-OE) 22lbs