I have a a 08 Cx-7 and when the turbo kicks in it sounds like air is rushing and I’m not the boost that I should. It seems to run fine other than that! Could it be a bad westgate?

 

From the inlet side of the Turbo you need to do a visual inspection and then carefully see if it spins freely and no wobble movement. If its dirty with oil residue or carbon anywhere chances are it time for a new core. Rebuilding a turbo is actually easy if you just get a assembled core. But if your game you can but a kit and do it yourself. The only down fall is a hyper balancing that you can only have it done. Most assembled rebuilt or new core are balanced Below is a few y tubes of Turbo I have had to work on that may be of interest? .

Here is a really badly worn Turbo.

This Turbo spins but never produced a good boost. You can see why....it sticks..

This Turbo was DIY rebuilt but he never achieved the boost he use to get. When I took it apart the turbine wheel shaft bushing was installed incorrectly and was binding. It was an easy fix to simply replace the bushing. The kit was inexpensive so I just went ahead and did a rebuild for him

 

Sounds like a boost leak. Split hoses, loose hose clamps, leaking blow-off valve. I don't think you could hear a faulty wastegate bleeding off into the exhaust.

 

Grim has some things to look at that are serviceable but the reason I suggested the TURBO itself has problems was because of the 2 high lighted comments in your first post. If the compressor and Turbine wheel are not spinning freely you will not have your normal boost and those wheels running slower as the air flow increase in the intake system, will create a louder then normal sound you are not accustom to hearing when you are throttle up in the RPM range.

I would look at everything the Grim and I suggested!