SLK230 Exhaust Leak?

Hi,

I have a 99 SLK230 (AUTO) and when I start up the car in the morning or after it has been sitting a long time, there is a definite exhaust leak sound from the passenger side and the car sounds like a volkswagen. The dealer says its the booster pump and the sound is normal upon startup. They claim only pre-2000 models do this...

Does anyone know if this is normal? Even when it warms up, upon acceleration I can still hear a slight bubbling exhaust sound.

Can someone tell me if their SLK230 sounds like this upon startup?

thanks!
-buidude