I have a 2011 SC XJL, for about 2 years now. The one thing I don't like about the car is the loose feeling in the rear when taking decent bumps or more so when turning corners under speed. It feels like a better sway bar would tighten that up, but I don't think that's an option.

Anyways, I know Dynamic mode is supposed to tighten the suspension up, but I can't tell a difference. Strangely enough, about 2 months ago I was hearing a noise that sounded like a compressor every time I got out of the car. This happened for about a week, and then I never heard it again. I also had not heard this noise/vibration previously.

Does anyone else ever hear their compressor or am I going crazy? Assuming I'm not crazy and I only heard this for a few days, that would leave me to believe it was faulty, but I would think on board diagnostics would catch it (hopefully).

 

As for rear sway bars, there are a 17mm and an 18mm. If I am not mistaken the 18mm was used in the SC V8s from 2013 on. This would tighten up the rear a bit as this along with an 18mm up front are used on the XJR.