I have a 2005 CC LE 4X4 with all the trimmings. So far I love everything accept the "thunk noise" under the dead pedal. After researching and a couple of visits to the dealer, found out that those who have Hill Assist/Decent, VDC and ABLS (antilock brake limitted slip) options, Once you accelerate above approx 40 mph and the computuer that controls these functions reads that none of these features were activated it bleeds off extra pressure that had built up in the master brake cylinder and unfortunately transmitts the relief valve sound thru the firewall to under your left foot. Nissan is aware of this and hopefully will come up with a solution to minimize this. The one tech told me maybe a reprogram or recalabration of the ABS/ABLS computer.