OK, here's the drill. I weighed my parts on my bathroom scale, which isn't very accurate because it says I'm 10 lbs to heavy, which I know just couldn't be right. I stood on the scale, with and without parts and figured the difference to try and make it more accurate for the really light stuff. A stock 67-8 Mustang coupe deck lid was 27.5 lbs. 1/4 panel extensions were 5.5 lbs. My CS deck lid was 27.0 lbs, taillight panel was 5.5 lbs, 1/4 extensions, taillights and scoops were 14.0 lbs for an INCREASE in weight of 13.5 lbs, without the stock taillights figured in. I would guess our cars are about 10 lbs heavier than a standard coupe and while that may cut our ET's by a millisecond, I would sacrifice that for the "look" any day. Hope this helps.
Steve ;D