Gabriel,

Welcome to the forum!

The Coupe's spring rates are 451 lb./in. in the front and 480 lb./in. in th rear. As was mentioned above, these are the springs that members cut to lower the ride height. I am not sure what the spring rates are on the SLK32AMG, but I was under the impression that they were less than the SRT6. If so, I would be careful about cutting them as doing so could cause you to bottom out your suspension during "spirited" driving.

As for the resonator removal, do a search as a few people have found that removing the muffler and leaving the resonator gives a better, throaty sound to the vehicle, but without the drone. The drone has been known to occur on some cars that have removed the resonator, and left the stock muffler in place. I can't speak from first hand experience b/c I still have the factory exhaust, but I am sure some of the other members will chime in on it.

Again, welcome! This is a great site with lots of info.

Cheers,
KrzyFast