I just noticed the following. Not sure if it's normal.

Park the car and place it in neutral. Gradually give it gas so the rpm rises steadily. Right before I reach 5000 rpm, I can hear a little boom and the steady rpm rise was paused (or set back) a little. Then it goes smoothly to red line.

Do you have the same thing? What would cause it?

I have a stock X50.

Thanks.

 

Does it do this while you're driving?

 

I can't feel it when I am driving. That's why I suspect this may be a normal characteristic of our cars when not in gear. We need another member to test his/her car and see if it's there.

 

Just tested it when the car is cold in the morning. No boom!

It only happens when the car is warmed up. So strange...