I'm trying to compile a list of all the performance mods that indirectly(or directly) cause your car to weigh less after being installed. Here are all the ones I could think of, feel free to list more...

-carbon fiber hood
-carbon fiber trunk/hatch
-flywheel
-header
-racing seats
-wheels & tires
-pulleys
-steering wheel
-short shifter
-lower control arms

...any more?

 

Some of those are pushing it (short shifter lol) but a couple more are-

-Exhaust
-Cold-Air or Short Ram intake

 

Some exhaust set ups are less than stock. Lightweight rims and tires. You would be amazed how much more unsprung weight will help. Springs/shocks/ rotors/calipers

 

man this list could be as long as u wanted it to be. depends how much cash u want to put into it

 

brake setups

 

Pretty much all "good" aftermarket pieces weigh less than their stock counterparts. And the "good" ones that are heavier are still fine because they make up for it in performance.

 

windows. Lexan windows are a good way to drop weight.

 

racing seats
titanium exhaust
light weight wheels