4" carbide all you need on the curves. Mine were hard steering as well, but able to get them a little lighter by adjusting front shocks to only 5 mm preload increased rear suspension center shock about 15 mm preload (ride and change as needed) and set my rear springs on M and transfer rods to max. I know mines an XTX and different than your RTX suspension, but I would change one thing at a time in the rear suspension and see what effect it has and go from there. Curves are still going to be alittle harder steering, but I'm use to it and like the way they hold to the trail!
good luck,
Pete