I have never owned a turbo vehicle before so I am not sure if the noise I am hearing is normal. I searched but could not find any posts describing this noise.

I have a 2010 SS automatic that I purchased with a bad turbo (Overboosting, then no boost at all). The turbo (including gaskets) was replaced and now it boosts normally and within range. The issue I have is the noise. Under full throttle it makes a loud whomp whomp kind of noise. The old turbo made this noise, too, when it tried to work during overboost. It is not the wheel bearings because the car did not make that noise when the old turbo was not booting and the car drives quiet and smooth otherwise. Is this turbo noise normal under full acceleration? Thanks!

 

No. Not normal.
You say it's boosting "within range". A stock turbo and tune should see boost numbers around 14-17 at full boost. If your's is stock and seeing numbers higher than that, you may have an overboost problem.

 

It is boosting to right at 15 at the most. No boost when cruising at speed unless you accelerate hard and it kicks in, etc. Any idea what could be causing that noise?

 

No idea. Your description of whomp, whomp really doesn't say much. Is it a loud noise ? How far between whomps ? Is it a low, muffled noise ?

1. Is this with the AC on ?
2. Back windows down ? (Having the back windows down is known to cause a helicopter type "waa waa" noise at speed)

 

Have a listen , it could be the stock spring in the bypass or blow off valve

 

I was able to determine the car is making the noise while sitting still. If you rev the engine it makes the noise, and since it is not producing boost when sitting still, I assume it is not turbo related. I was able to get a video. Any thoughts?

 

Those files don't open.

Could be the flex pipe.

 

https://www.chevyhhr.net/forums/atta...n-img_5539.mov

 

I could open and listen , but it was to short of a video to determine the noise. Could be belt tensioner pulley , could be serpentine belt .