Last June 2017 I went ahead & purchased the Intermediate Slinky rear coils. When I originally purchased the rear slinky coils they just had 160/320# heavy coils in stock, I didn't want to wait another 2 months for the lighter duty coils. The heavy coils were just that... I run a light rig so the normal 160/270# Intermediate coils suite my needs much better. If I had a dual swing out & spare tire out back the heavy coils would of been just fine. As far as specs... turns & free height are basically the same but the wire diameter looks to be a couple mm thinner.
The ride is much more supple but the handling is really good. I only run approximately 250 lbs overstock in the rear so I can feel that I'm still in the 160# rate then when my family climbs in I can feel it hit the 270# rate. The on pavement ride is like a stock feel same as the heavy coils. The real difference is on the trail... they compress more & soak up some of the heavier hits. Also when I wheel solo... at the end of the day my back likes me better.