Within the last 3 days the turbo has developed a new noise. I'm not sure if it's best described as a whine or a howl but it is definately a new noise. I would say it's in the mid frequency range, neither very high nor very low frequency. It appears when at cruising speed and disappears if the engine is put under load or if the accelerator is eased. If just maintaining a speed, regardless of if it's a high speed or a relatively low speed (35 mph) the noise is there. If I accelerate or ease off the throttle it stops. If running at 65mph for an extended period of time it really becomes a drone that that just irks you. Never had any turbo problems before and there are 130,000 miles of the truck. I'm running a K&N air filter, Flowmaster Exhaust, Van AAken module, and have 275 RV injectors installed. Any ideas on where or what to check or look at would be appreciater.