[enigma]

IIRC: The stock seats are 70-80 lbs each. Compared to ~20 for a lightweight seat. The seats in my other track toy are ~15lbs

Now, having said that there is no way I am swaping the seats. The center of the car is the least harmful place to have sprung weight. You will be giving up a ton of comfort for very little gain.

100lbs of sprund weight is going to make about a 2% change in accelration and less in cornering.

Lightweight wheels, brakes will help the most since they are unsprung weight and also mostly rotating weight.

I once went through this exercise and when confronted with the cost asociated with lighting the E46 I just spent a little more and got a 1600lbs lighter 2nd car.

I have tried running the e46 without the rear seat and the diff/fuel pump noises drove me nuts. Not to mention having to explain what was wrong with the car when I picked up the date.

Remember having to live with the modification and loss of confort, convience, or utility is a cost just as much as $$$


[edit] My race wheels & tires are 47lbs for a 18x9.5" rim with a 275/35-18 tire. about 4lbs less than stock compared to the same size rears.