Ultra Sport

When I start my car in the morning and it sits on the higher idle for a few minutes I get a rather strange sound coming from the back of the car.

You can only hear it when you are outside but it almost sounds like a leak or something.

Start your car after its been sitting a while or in the morning, walk around to the right rear wheel and see if you hear a hissing sound?

It might be totally normal but it sounds strange.

My car is stock aside from a chip