The car: 08 997.1 Turbo
Mileage: approx 19k
Suspension: HR springs and sway bars
Transmission: manual

The problem: when braking (while in neutral) even on smooth road surfaces, at around 15-15 mph a pretty prominent jolt can be felt through the entire car...almost as if there was a big thing in the trunk that rolled forward and hit. Pretty much never fails to occur. I have a hunch it's something loose/worn in the suspension- since it wasn't there before lowering the car a couple months ago. Handling and other normal driving feels completely fine otherwise.

Any ideas?

Thanks guys!

 

Worn transmission / engine mounts could be the problem.

 

thanks for the suggestion - I can have that checked out for sure.

I read about some Cayenne owners having a similar issue with the "thud" coming from their undercarriage when slowing down - but can't seem to find any posts from 997 owners.