[cruiser100]

Turbo's always make a "whislting" sound, some just more than others.

Questions:
- Has the sound gotten louder lately?
- Has there been any recent work under the hood?
- Any exhaust work lately?

Try this: block the vehicle (tires) and set the p-brake so the vehicle won't move. Start the engine, put the trans in "N". Have someone gently rev the engine up while you listen under the hood to try to pinpoint the sound. The turbo gets VERY hot, so don't touch it until it cools off and please don't toss water on it while its hot... yes, i've seen it done, not pretty.

If it is coming from the turbo itself, you'll want to check gaskets and bolts on the downpipe, intake and exhaust manifold connection. A lot of intakes have just a pipe and a clamp, make sure the clamp is tight and the intake pipe doesn't have a hole in it.

Also, remove the intake pipe and turn the impeller with your hand; it should spin freely. Also look for oil deposits while you have the pipe off.

If the impeller doesn't spin freely, you may have a bearing issue.

If you see oil, the oil seal may be leaking; it'll need to be replaced.

If it's not the turbo, come back and post where the noise is coming from and I'll try to give you some pointers.