It would depend if your using a FC cage like I am ! If that's the case it can be pretty low ! My sfi book is at home so I wouldn't be able to tell you for sure right now ! I know the nhra says that iirc it can't be low than 4 or 6 in where the belts come out the the seat ? As far as removable I'm not sure it would fly but I never tried so not sure ! I just figured only people getting in the back seat will be my kids, and they love to climb all over in there now. So it's not a big deal to me of them !