PUREVIL, post some pictures of your issue... I'm running TEIN RE's and don't have that issue. Not sure which collar you are referring to?
Is it the spring pre-load? Or the ride height adjustment collars? I didn't have any clearance issues on mine.
+1.
You can adjust the ride height one of two ways:
1- the collar at the bottom of the spring (where you would adjust the ride height on any other coilover -like your KW)
2- the Tein-specific collar at the base of the suspension.
The whole body of the Tein is threaded, allowing you to adjust the ride height without reducing your travel. On a normal coilover, as you lower the car, you loose suspension travel. Tein has a separate ride height collar at the base of the green housing (you twist the ENTIRE threaded body to change the ride height) from the 'spring pre-load' collar that is a double locking collar.
By changing the ride height of the 'preload collar', you are reducing your travel (Tein's don't have a lot of travel to begin with, so its not a good idea from that stand point) as well as most likely causing you the problem of the 'preload collar' hitting the control arm at a relatively high ride height.
Loosen the top double-collar (pre-load collar) and tighten the collar against the spring as much as you can by your hand (you only want the 'pre-load' hand-tight, so you maximize your travel, and pre-load it enough so it won't rattle over bumps). Then use the spanner wrenches to lock the bottom and top perches together. From there go to the single bottom collar that locks against the threaded body, loosen that one and the twist the entire black threaded-body to your desired ride height.
If you're not going to corner-balance your car (which is expensive), make sure you and your friend measure the distance between the top of the spring, and the bottom double-spring perch and make them even left-right (so the pre-load is the same and the height is the same. Then measure from the bottom of the double-spring perch to the bottom locking collar and make sure that distance is also equal right to left.
It may sound silly (and I dont know if its even possible) but make sure you have the fronts mounted up front, and the rears on the rear (the front assembly and spring is shorter than the rear).
Good luck!