The problem with running a 5 pt harness in a car that has no cage is that if you were to flip your car, you are stuck. With a normal seat belt, you can lean, bend down, etc. If you flip with the harnesses on, your roof will collapse with no cage to support it and your neck will be snapping like a fire cracker. To each his own as I see people still doing this.

For the record, I have sparco 5pts in my car.