RIKI

I am sick and tired of a whistling noise in my LS430 .the noise starts at about 25mph . the car has just 12000 miles .i started noticing the noise around 5000 miles . original dunlop sport tires hv been replaced with michlein tires , still noise persists.so it is not a tire problem . i hv gone to two different lexus dealers , but they r clueless .any suggestion to fix the problem ?