My 04 had this noise since new, I even test drove a new 05 at the dealer and it had the noise. It gets really annoying when towing since under load and light-medium throttle and 2000 RPMs make the whistle occur. I hate to say it but unless they changed something in 06/07 then they all do that. It is very high pitched so I bet some people can't hear it even if it's occuring.apx_06 said:Have the exact same problem. Mine started last month at 27k for the first time. Dealer tried to repair it 3 times then told me it was a normal condition and was common on Titan’s and there was nothing they could so. I went nuclear and wrote a 4 page complaint to Nissan and filed a complaint with the BBB Autoline. Long story short, I met with the Regional Manager this morning 10/25 and they have agreed to replace the throttle body. According to them this will fix the problem. We will see. Basically this is a defect that is caused by build up in the throttle and rather than do anything about it they simply say it is normal. Good luck and I will post an update next week to see if the fix worked.