Dave S., my 1990 1.6 weighs 2020 lb with cool suite/2 gallon water, 1 gallon safety fuel and no driver or driver gear. Have NASCAR side protection tubes therefore doors are gutted, but still have triple thick inside top of door. Let's presume Alberto's car same weighs 2128 lb. without driver and gear. That my friend is 108 pounds more than my 1.6. That is a lot of friken weight.
I don't disagree with your tenths and hundredths, but that's not the point of this thread.
He asked why those things couldn't be deleted. I was talking about what he wanted to gut that wasn't allowed by the rules, not what he should be gutting per the rules. If a builder is leaving 100# of legal dead weight, they've missed a bunch.
As for those items that can't be deleted...
1990 base model ( happen to have all these things off the car and in the shop, never put the kack back on the car)
heater core 6 lbs 4 oz
blower 4/7
we can call that 11 lbs
headlight bracket 1/12 x 2
headlamp and mount 3/14 x 2 (I left the pop up plate off as you'll need it or something like it to cover the hole in the hood)
retractor motor 1/6 x 2
both light assemblies let's call that 10 lbs plus another 2 or so in marker and signal, 12 lbs (didn't do rears)
wiper arms 14 oz x 2
wiper rod 1/6 x 2
wiper motor 2/6
wiper bottle 1
wiper system lets round to 7 lbs
Not bad, about 30 lbs, but if you're in an area where it rains (he's not, I'm not) then no racing those days. No way deleting that will be allowed.
The other brackets, airbag wire, etc, maybe 10 lbs. Maybe. Let's be generous and say 20 lbs of new parts to delete. Unless you are at the pointy end, it's not really going to do anything for you.