There's an SRT6 engine and transmission for sale over in the classifieds forum. That's about the only way I'm aware of that you're getting forced induction in an NA Crossfire, and the only reason I can think of to do that is if you just have to have a 6 speed SRT6. If it wasn't my daily driver, I'd be tempted to build a 6speed SRT6.... Otherwise, hate to say it, but sell it and get an SRT.