I spoke with Dan and Mike in detail about ohlins suspension. And they have posted about it before in older threads on the net.
The 30 mm NIX kit is the latest suspension technology from ohlins. And the newest stuff is out due to improvements. So yes, this cartridge kit is better than the older Ohlins FG43 fork variants for the RC51, which use different and smaller valving.
However, Kyle USA basically makes the 30 mm NIX kit fit the OEM RC51 forks as it is not a drop in for the bike. Among other things, the forks have to be lengthened and one sees the large adapters on top. If you don't mind the looks and want to get the best, get the kit. Unfortunately, aesthetics is important to me, and the look of the kit bothers me. That's a personal thing though. Others aren't bothered by it.
And while the kit is an improvement, it is not huge. IME, many riders wouldn't feel an appreciable difference over the older ohlins forks for the RC51 (well set up), and 99% of riders + wouldn't be able to take advantage of it. And we're talking track here, as on the street one won't be riding to the extreme where those differences become significantly discernible. Also, there are upgrades for the FG43 ohlins forks for the RC51 that make it better, closing in on the 30 mm kit capability. The 30 mm kit has a notable track advantage of very easy spring changes, taking around 8 minutes I've been told.
Both options are great. Each have some minor differences from the other to consider.
Last edited by kwtoxman; 12-31-2013 at 05:27 PM.