Fox's Evol sleeve is visually similar to our Corset air can, and based on the same concept. However, the Corset is still a big improvement over the Evol. Here's what the differences measure up as.
It's immediately visible there that while the Evol is an improvement over the old style Fox sleeves, the Corset's initial spring rate is way lower than that of the Evol. How much though? Quite a lot - roughly half, even with enough pressure in there to have a considerably firmer mid and end stroke.
For the substantial majority of leverage rates, including but certainly not limited to VPP, the Corset offers a marked improvement in performance over the Evol sleeves. There are a few bikes out there though that should stick with the Evol or old style cans, such as the Norco Range - these are extremely progressive and require too much sag with the Corset. The lower sag & lower progressivity of the Evol sleeve works better on these, and the old style cans work well too, though ideally a coil shock is best suited to very progressive frames. The same applies to other bikes that are extremely progressive - in these cases you can expect better results with a coil shock than any air shock.
If you're not sure whether or not a Corset is suitable for your bike, shoot us an email and we'll discuss what options will work best for you.