[samM376']

Consider getting some Recaro Pole Positions which are capable of using any harness system and stock seat belt positions
I don't drive using my harnesses on the street, I opted for a profi clip in style harness so its on for track days and off for the everyday, same kits available for E92's
My E46 is very light in the rear, a simple 40 lbs doesn't affect the car dramatically as posted above. It would actually make the tail easier to feel around and settle the cars weight easier under hard acceleration like coming out of corners after straightening out
If you're not getting corner balanced for the weight offset, than theres really no point unless you're making a 100+ pound offset