Whistling sound under heavy load... is it a boost leak? (2007.5 LMM)

[HeavyHauler_Dave]

I’ve got this high-pitched whistle that only happens when the turbo is at 20+ PSI. It’s not the normal "turbo whine." Is it the boots? Clamps? I’ve checked the obvious ones, any "secret" spots these LMMs leak boost?

 

[SteelMetric]

Check the intake horn-to-turbo connection. That o-ring gets old and leaks at high pressure. Also, look at the EGR up-pipe—sometimes they crack at the flex joint.

 

[BoltAndBeam]

Buy a "boost leak tester" tool. It’s the only way to find those tiny cracks in the boots that you can't see with the naked eye.