S4 springs vs A4 springs (help)
 

What are the differences between these two spring sets???? Is the ride height at all different? Can the stock S4 springs be mounted on the stock A4 shocks? Is it worth doing performance wise?

Any thoughts would be appreciated.

Not a good idea. My S4 Avant was higher than my non-sport A4.

don't do it.......S4 springs are not a good upgrade for your car.......
 

They are only slightly stiffer and lower than the "non-sport" A4 suspension, and not as low or as stiff as the "sport" A4 suspension.

If you currently have the non-sport package, you're better off getting the A4 sport package. If you currently have the sport package, the S4 springs would actually raise your car and make it softer.

Also, if you have a 1.8, the S4 spring rates are such that the front of your car will sit too high, since the S4 is much heavier.

Don't do it.