The FEs can be street titled. The 4CS fork was a last minute throw together and not fully tested. Not impressed with the performance. The fwd mount on the linkage bolt is easy to mess up, if you have worked on a KTM also you know what I mean. It has a nut with a flat side that barely engages and when you go to remove it if you don't heat ot up to soften the 20lbs of loctite, it will back off 6mm and bugger up the frame. There is also not way of holding it. Air box noise on the 4t bikes is still the worst in the industry. Not sure when KTM is also going to realize the tapered spline shifter is a crap design too. I have too many rides buggered up from a KTM shifter slipping and or break/ coming off. But, I get a lot of them in my shop so keep on buying them fellas and I will keep fixing em up 
I put a large flat blade screw driver between the frame and linkage bolt flat side to take up the slop for loosening and tightening. Never had a problem with any of my three KTM's and didn't have to use heat. I haven't noticed any unusual air box noise either? My RMZ450 air box... that makes some noise! I do agree that the SX/SX-F 4CS 2015 and earlier 4CS forks suck! I had to send my 2015 forks off to WP Factory Services to get them manageable. My understanding is they perform okay on the off-road models just not the SX/SX-F's. Stillwell and Dick's have also solved the SX/SX-F 4CS fork problem. They have some videos on it.
https://www.youtube.com/watch?v=FDRhvmoB9lE
