Thanks To se7ensectoolate For This Article!!

Here is an overview of weight reduction that was done on a friends Civic. Measurements were on a bathroom scale so they might not be 100% accurate. This was preformed on an 04 Civic, but the same principles can be applied to any generation.

Free-
Spare tire 24lbs
Tire iron and wheel bolt 2lbs
Jack 3lbs
Center trunk carpet 1lbs
Cardboard over spare tire 7lbs
Driver side back seat 12lbs
Passenger back seat 7lbs
Back seat bench 8lbs
Passenger seat 35lbs
Center hinge trunk plastic 1lbs
Driver side trunk carpet 1lbs
Passenger side trunk carpet 1lbs
4 mud flaps 2lbs
Driver rear panel 5lbs
Driver rear pillar 1lbs
Passenger rear panel 5bs
Passenger rear pillar 1lbs
Side sills 2lbs
kick panels 1lbs
Front carpet 13lbs
Rear seat belts 7lbs
Entire rear deck inc. speakers 10lbs

That's about 149 lbs so far, for free.

Now 1 gallon of gas weighs 6.2 lbs. I try to keep a 1/4 tank when racing and never more than a half daily. So lets do worst case scenario. A Civic has a 13 gallon tank.
13 x 6.2lbs =80.6lbs
Worst case 1/2 of 80lbs= 40lbs

So we're up to 189lbs.

My exhaust, header and intake should add up to 11 lbs less then the stock components for an even 200lbs.

Wheels. 12.5 lbs 17" forged Velox Pg5-s.
2.5lbs less per corner of unsprung weight.
Kyokugen lug nuts 1/4lb less per corner.
So 2.75 x 4= 11lbs of unsprung weight, which actually has a greater effect than sprung weight.
Get the 15" Spoons (8.5lbs) and thats 4 more lbs per corner

Oh and for EX owners your wheels are 5lbs heavier than my dx 14's so that would be another 20lbs of unsprung weight reduced.

More things to reduce weight.

Door panels and anything else not needed behind them 5-10lbs per side?
Stereo 5-10lbs?
Roof liner 5lbs?
Sound insulation 15-35lbs?
AC and components 50lbs?
Center console 5lbs?

Stuff that costs money.

CF hood 5-10lbs?
CF trunk 5lbs?
CF Fenders 10lbs?
Racing seat 10-15lbs
Lexan rear windows 15-30lbs?
Lighter battery 10lbs?

(These number are just an estimate though, not 100% accurate.)

A few notes on rotational weight reduction.
Reducing weight does not magically make your engine have more HP. It simply makes it so that the HP you do have has to accelerate. Less mass = faster acceleration.

Also, you have to look at where the weight you are removing comes from. For acceleration, reducing Rotational weight (any thing the engine has to get to rotate) will have a 70% more positive effect then just removing weight from the chassis.

Meaning, if you reduce your wheels weight by 10 lbs (total weight removed from the drive wheels, not per wheel), it will have the same effect as if you had removed 33 LBS from the chassis...

so, the stock 15" steel wheels weigh 19lbs... if you reduce that to 10LBS each.....
(19+19 = 38LBS on the drive wheels stock. Vs 10+10 = 20 LBS on the drive wheels... = 18LB reduction in rotating weight, so it will feel as if you removed 60 LBS from the chassis (18 is 30% of 60).