I have RCI in my car and they are fine. If your buying new ones they will be legal for a few years, do double check they are SFI rated though.
I find due to the way you sit in the car the pull-down straps work better for the shoulder and the pull-ups better for the lap belts and sub-strap as you can pull everything towards yourself. Plus in a bucket the seat can get in the way of a pull-down lap belt. My .02 on those.
As for mounting, they sell hardware to bolt them in, just make sure you use reinforced places to bolt them to, like your stock seatbelt locations. A cage is best of course and don't buy the harnesses longer than you need to as the longer they are the more they can strech.
Def. get the Camlocks, much easier to use!!