2012 gt. I just had a shop throw in all new suspension parts. 1.5" lowering springs. Kyb struts and shocks. Whiteline front and rear sway bars with adjustable links. Adjustable panhard bar. Outer tie rods. Rear lower control arms.
There was a thunk in the back rear which I knew would get taken care if. However, now there is a big ol thunk in the front right. Shop I brought it to went over everything and it's all tight and right. So the question is, what might it be? It sounds like maybe a ball joint. But supposedly they are good. Just wondering if it could be something else now that it has been lowered. I'm going to do some more investigating this weekend. I trust the place I brought it to. All they work on are mustangs. And for him to say they can't figure it out is slightly puzzling. To me, it can only be so many things. Any help is greatly appreciated.

 

With the lowering, did you change the bump stops on the rear axle? If you didn't that could be the source of your thunk sound. The stock bump stop is too tall and the car will hit it giving you a thunk and a rough ride.

You can put the Ford Performance shorter bump stop on, or simply cut the top "nipple" off the stock one.