You really get what you pay for when it comes to harnesses. I found the crows to have the highest quality belt material that is very pliable and doesn't take a set if left in the same position for a long time. Others I've tried over the years get difficult to adjust after a short time of use and just seem cheap compared to the crows.
I would recommend getting the Crow 5-points and once you install them decide whether you want the anti-submarine, "crotch", belt. I went with the Crow 4 points and sometimes if you don't cinch down the lap belt tight enough before tightening the shoulder harnesses, the lap belt will ride up making it a little uncomfortable.
The new harnesses will bolt to the existing mounting points for the lap portion and the shoulder straps wrap around the roll bar behind your seat. This installation will not require any permanent mods to your RZR. For more info on mounting, do a search for "harness install" or "harness mount" and others have done it this way and other ways and documented their install, including pics, that make it very easy to do yourself.