Welcome to SLKWorld Steve!!
You'll want to install a K&N air filter so the car can breathe a little easier.
The pulley kit is a good idea, I'm planning to go with the ASP when the time comes.
A MAF relocation mode will make a difference with the lagging of the supercharger. Here's a link to get you started.
http://www.benzworld.org/forums/r170...MAF+relocation
Definately get a roof module, there are a couple out there, I have the EasyRoofSLK
www.simpleroof.com. Excellent & inexspensive!
I clear plexiglass wind deflector is much nicer than the mesh one. I got mine here
http://www.windrestrictor.com/SLK170_Home.html. Really nice folks!
That's all I can think of right now.
Good luck and post some pics of your ride!!