I spoke with Nissan Motorsports in regards to the Chassis Dampeners on the NISMO. They explained to me that it helped with the chassis harmonics
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The dampners were tuned to the car's "frequency" and factory suspension setup. They mentioned that if you adjust the suspension (i.e, Stiffer Sway Bars, Chassis Braces, coil over suspension), you have altered the vehicles "frequency" and could possible negate any of the benefits of the Chassis Dampners.
Again this is what was explained to me by the guys at Nissan Motorsports.