I have always added a cold air intake to my vehicles but i'm not sure about doing that to the Merc.
I have heard some other things that made me nervous such as, underdrive pulleys?, changing the pulley size on the supercharger to a smaller one for faster spin?, those are scary ideas to me.

safer idea....i've heard buying the chip for the computer? others have said thats worthless

the big move I heard was changing the cam to a racing cam to see HUGE gains. for several thousand bucks. i'm not sure if i want to do that. car has 70k miles. no problems yet...?