Well no, you can't. You have something similar to a blowoff valve already and its controlled by your computer to release boost if the computer feels that the engine will be damaged. It won't give you that lovely blow off valve sound though. Putting a turbo on a supercharged engine would definately be overkill in most cases. I've heard of it being done but heat is a BIG problem and you would never pull it off without an air-to-water intercooler, and a big one. I've heard your engine is capable of taking 22-27psi of boost but that doesn't mean your parts will stay together, thats just means the block won't crack. If you want more performance get a smaller pulley.
Stuff got done.