Growling noise


First off. i drive a 2008 Cobalt SS turbo. its been a good car and I haven’t had any major problems with it aside from the small stuff.

Well for the past few months I’ve noticed that, whenever i drive in heavy rain or in snow etc I will get a loud Growling/whining noise from the transmission area. Now it will do it while in Neutral, 1st etc and when stopped it will go away. If I stop the car for a few moments, the noise goes away until I hit another puddle and then it comes back again.

I also feel a “knocking” in the shifter and I’ve noticed its vibrated really badly for awhile now.

the caveat to this is it ONLY does it when its wet outside. I’ve taken it to GM a few times, and even showed the service manager the issues when it was raining out and he said everything was fine. The car never did it when I first purchased it.

I should include that there are some aftermarket modifications on the car. Catless downpipe, new intercooler, lowering springs. stock exhaust and stock turbo.

Any help would be appreciated as I’m at my end with this thing

Have the transmission mounts and motor mounts been checked. I ask because of the vibration in the stick.