So... this is just my uneducated opinion, and I really feel like an old man here but...
These look like they are effectively adding preload to the springs. That means less down travel for off-roading and potentially less up travel if the spring runs out of compressible space. None of those are great, but you should be fine overall as most aftermarket coil-over suspensions have adjustable pre-load.
The next issue is that they claim that this does not "alter suspension geometry". I agree that these collars will not allow for travel outside of the factory limits. However, you will have drastically changed the angle of the arms and the static position of the ball joints. Any company that wants to be even kinda serious about off-roading always adds a uniball upper control arm to any IFS lift.
Finally, there is no way to inform the computer of the change and allow it adjust accordingly. This may not seem like a big issue, but it could have unforeseen consequences. I know that on my current truck that came with Magneride, the sensors needed to have extend arms or you would get a very harsh ride. This was on a truck made for the street with the goal of comfort. The system on the TRX is much more sophisticated and tied into many other systems. For example: the extended suspension could cause the "jump detection" to be always or overly active. This could result in the transmission allowing slip to protect itself but instead its just always driving around in a slip condition causing accelerated wear. There are many interconnected systems on this truck. Adverse affects on the traction control system is another one. I worry that these may cause issues that do not show themselves until its too late.
Basically, these collars seem like the equivalent of a high school kid cutting the springs on their civic only with a much more expensive and complex vehicle.
/rant
I am very willing to be educated otherwise, but this is my first impressions. I know that some of us are very anxious to see the aftermarket start to make meaningful suspension upgrades to these trucks. We need to be patient and wait for some fully baked solutions.
www.foutzmotorsports.com
