Fixed

 

1) thats right on par for what a stock s4 puts out.. 7 to 8 psi.

2) could be upper control arms, could be motor mounts.. i think more than likely your control arms..

 

Where is the rattling sound coming from?

 

it sounds like it comes from underneath? (suspension possibly?)

 

Front or rear? We can help diagnose the problem better with the more specific you are. There are several components in the suspension that could be culprit.

 

ok well the rattling sounds like it is coming from the rear, possibly underneath the car. im not sure what it could be. i've made a short list of what it could be.

-control arms
-spring seats
-loose something?
-sway bar
-...

anything will help, really! thanks

 

If I had to guess I would first check the control arm bushings and sway bar bushings and links.

You need to neutralize the sway bar to check the links. For example; with the car on the ground or with the wheels loaded evenly (like on ramps or a drive on rack to get under it) so that niether wheel is higher or lower than the other.
Or if you can, disconnect one side and see if either side has play.

You can check the control arm bushings by jacking under the lower arm as close to the tire as possible just enough to get the wheel of the ground. This will keep neutralize the suspension on that side enough to wiggle the wheel to check for play.

A good visual inspection never hurts either.
Let us know what you find or if it's something else.

 

Off-topic
RED1 did you photoshop your bumper lol?