FWIW, a buddy of ours surprised us at the track this past summer. He was running his all motor VE. The car went 13.6-8(something like that). He took out the extra crap he had in his trunk like tools, jack, 2 rims/tires he drives on the street. Figure about a hundred pounds of shit give or take. The car was then running consistent 13.3's. I've heard the same thing as you Aaron. Who knows, lol.
Once the weather warms up I'm going to remove the dash and pull out any unnecessary weight like a/c crap and firewall blanket. Carpet is coming out then breaking out the cutoff wheel and cutting away the rear area of the car since I have a roll bar. Spare wheel well is going bye bye.
For a quick track day, we always removed seats, door panels, jack, spare and any random crap bouncing around.