The vibration reducing u-joint is a modification that I believe was originally installed by Bill Robertson a few years back. The stock DeLorean steering system has no isolation between the front wheels and the steering wheel. Most car makers address this issue with a rag joint, however, the DeLorean does not have enough room to accommodate a rag joint. Thankfully, Borgeson makes a vibration reducing u-joint for small clearance applications. According to Borgeson, the vibration reducing u-joint provides vibration reduction similar to that of a traditional rag joint.
With the benefit of the vibration reducing u-joint, LCA braces and upgraded LCAs, my DeLorean is almost as comfortable to drive as my 85 Toronado.
I know a number of owners who have done this upgrade and I haven't heard any negative feedback.
Back when I installed the vibration reducing u-joint's, I had to order the parts directly from Borgeson because they weren't available from any vendors yet. But now you can order the entire setup from Rob Grady. :-)