Hello! I'm Rixster...
I'm going to see if I can help you out here but I'm going to need some info first to get started...
How long has this been going on?
Have you performed any recent modifications?
I just bought the car. Went to dealer twice and everything are OEM original.
Well I did a bit of research on this last eve. and I was able to find a service bulletin that might help you determine your case.
Check Out this bulletin #06-06-01-018
Bulletin No.: 06-06-01-018
Date: August 02, 2006
Subject:Information on Very Faint Engine Whine Noise At Speeds of 0-48 KM/H (0-30 MPH) At 1000-2500 RPM On 3.6L LY7 Engine
Models:2004-2007 Buick Rendezvous2005-2007 Buick Allure (Canada Only), LaCrosse2004-2007 Cadillac CTS, SRX2005-2007 Cadillac STS
with 3.6L V6 Engine (VIN 7 - RPO LY7)
A very faint engine whine-type noise heard at speeds of 0-48 km/h (0-30 mph) at 1000-2500 RPM may be caused by the primary camshaft drive chain. This type of noise may be amplified by the vehicle's body structure. The noise may be present at idle (hot or cold) and, in some vehicles, this noise may be louder.
GM Powertrain Engineering states that this type of noise is characteristic and/or normal for this engine. No abnormal engine wear or internal damage will result due to this noise condition.
If an engine whine, whistle or ringing-type noise is heard from the front of the engine and increases in intensity as the engine RPM increases, refer to Corporate Bulletin Number 05-06-01-013B.
An engine noise primarily around 1600 RPM that can be described as a howl will typically be coming from the exhaust system. This is also considered a characteristic and/or normal type of noise.
This has been copied from a public forum...
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If there is anything else I can help with please don't hesitate to ask.
This answer did not answer my question exactly. The resonance noise is at exactly 1700RPM. It practically doesn't do it at all when it's cold, but once it warms up the noise makes it a little uncomfortable in the cabin, especially since 1700RPM falls right in line with about 45-50mph which is where most driving time is spent.
Another post I found said: 'We had a resonance drone/vibration in our Tahoe at a certain speed. Took it to the Chevy dealer and they were aware of it. They installed a clamp on weight at a specific place on the exhaust that completely eliminated it.' This cound be the answer I am looking for. Will take to the dealer to see if they can add some clamp to the pipes.
Sounds good! I'm kinda curious now...