5 point harness in a car w/o roll cage...How to do it?

What type of seats are you using. In my Duster I had a set of poly RCI seats that I just mounted the upper belts to the back of the seat. Problem 1. In an accident it could have folded the seat with me in it. 2. It was not legal at any track. 3. If you were to take a long Y belt to the floor in an accident it could fold you and the seat because it will pull down on you and the seat. I would run a main cage and then build curved back bars that go down to the trans tunnel and mount my belts to the bar behind the seat. That way you can still access the back seat through the center but have some added protection.