So, your trying to measure every lb in a luxury sport racer? Pull the AC, pull the rear seat, pull the dash (replace with an aluminum shell to hold the tach and spedo). But, is that really the car you paid $70K for? If you do that, why have a muffler? Pull the cats too, carpet. Strip the trunk and headliner...
If you're willing to pull the nice comfy seats and replace them with lightweight ones where are you drawing the line between removing comfort and reducing weight? The things you are doing might add up to 100 lbs. Will that really make a handling difference and wouldn't it be cheaper from an acceleration and cost/benefit perspective to add horsepower?