I posted this in another weight reduction thread but I guess I should add it to the "official" thread here. 
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For those of you looking for every possible pound reduction for track night (easy removal):
Carpeted OEM floor mats (4): 4lb 3.2oz
Owner's manual and related booklets (assuming you normally keep it in your glove box): 2lb 3.6oz
All 5 headrests: 7lb 0.0oz
If you want to leave at least your driver side headrest in place (probably recommended): + 1lb 14.0oz
Thus, 4 headrests: 5lb 2.0oz
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For those of you looking for every possible pound reduction for track night (easy removal):
Carpeted OEM floor mats (4): 4lb 3.2oz
Owner's manual and related booklets (assuming you normally keep it in your glove box): 2lb 3.6oz
All 5 headrests: 7lb 0.0oz
If you want to leave at least your driver side headrest in place (probably recommended): + 1lb 14.0oz
Thus, 4 headrests: 5lb 2.0oz