Listed below are some easily removable items:

1.  Passenger Seat (37lbs) - Removing the passenger seat is a very easy and effective way to give your E46 a small boost in power.  The nice thing is that the seat is only held in place by 4 bolts. 

2.  Rear Seat (29lbs) - The rear seat is a little more complicated to remove than the passenger seat. When removing just remember where everything goes and it should be easy to put back in place whenever needed.

3.  Rear Seat Cushion (10lbs) - The rear cushion should be removed at the same time as the rear seat.

4.  Floor Mats/Front and Rear (6lbs) - This has to be the easiest weight reduction available for the E46 owner.

5.  Tire Floor Cover (3lbs) - The tire floor cover is right underneath the rear hatch carpeting.

6.  Spare Tire and Jack (32lbs) - Another easily removable item.

Total Easy Weight Removal = 117lbs or about a 7.8hp increase on 330 , 6.3hp on 323, and 11.4hp on M3.

Intermediate Skill Weight Reductions

The weight reductions included below can even prove more effective than some of the reductions included above.  However, once you start removing these items you are taking away from the cars overall appearance and in some cases its more predominent ammenities.

7.  Air Conditioning (40lbs) - Removing the air conditioning will net you a reduction of about 40lbs.  Be sure to remove everything from the engine as well as behind the dash.  Should be completed by the experienced only.

8.  Front Hood (50lbs) - Replacing the Front Hood with a lightweight fiberglass or carbon fiber hood is a great way to remove some weight around the front end of the car.  Total weight reduction will be close to 50lbs or greater depending on the aftermarket hood you choose..  If you dont intend on replacing the entire fron hood you could also remove the sound dampener on the inside of the hood.  This should help in cooling your engine a little.

9.  Stock Wheels (23lbs each/replacement weight from 17 lbs each) - Replacing the wheels is a must for anyone seriously interested in increasing there cars performance.  The stock wheels are quite heavy and can be replaced with a variety of aftermarket models.  We would suggest searching for lightweight wheels.  Replacing your wheels with lightweight wheels will dramatically increase your cars acceleration.  We suggest not going over 19 inches if maximum performance is what you desire to achieve.

10.  Front Drivers Seat (40-60lbs/replacement weight from 14lbs) - Replacing the two front seats in your E46 with lightweight racing alternatives can save you a dramatic amount of weight. We suggest going with lightweight carbon fiber or fiberglass seats.

Total Intermediate Weight Removal = up to 242lbs or a 16.2hp increase on 330, 13hp on 323, and 23.6hp on M3.

More Weight Reductions

Stock Flywheel - Can be replaced with lightweight aluminum flywheels or machined down in excess of just 10lbs.

Stock Steering Wheel - Can be replaced with lighter performance steering wheel with no airbag.

Airbag Removal - Can save some extra weight as well.  (Not recommended for normal driving)

Interior Panels - Both the drivers side and passenger side front door panels as well as the rear panels can be removed and replaced with carbon fiber alternatives to save in excess of over 40lbs.

Stock Speakers - With a weight of over 2 pounds a piece these can also be easily removed.  The stock stereo, amp, and subwoofer enclosure can also net a good savings in weight.

Rear Hatch Cover - This can be removed and replaced with carbon fiber alternative.

Roof - This can be replaced with the CSL type carbon fiber roof which will save in excess of 23kg's.

Trunk - Can be replaced with lightweight carbon fiber trunk. Savings of roughly 11kg's.

Front Dash - Can be replaced with carbon fiber alternative netting a savings of close to 60lbs.

Replace Stock Exhaust - The stock E46 exhausts weigh considerably more than some of the aluminum aftermarket exhausts.  We suggest going with a full cat-back exhaust such as those offered by Active Autowerke.

Wiper Motors - Although they are generally needed under almost all driving conditions they CAN be removed if need be although we do not personally recommend it.

Carpet - Removing the carpet as well as the carpet lining underneath will reduce the cars overall weight by close to  40lbs.  Removing excess wiring and bolts and brackets will also net you a reduction of close to 10lbs.

Total Advanced Weight Removal = Approx. 335 lbs or about a 22.4hp increase on 330 , 18hp on 323, and 32.6hp on M3.