What kind of CAI do you have? A good CAI is a great starting point. NeedsWings CAI is the best for the Crossfire. TVT does some great work for the NA XFires. Here is a .pdf file for some performance packages that they provide. http://n.b5z.net/i/u/6138924/i/Crossfire_PACKAGES.pdf

Asking how to best improve your NA Crossfire is a better approach than your original, and I am sure that other will chime in with advice. As I drive an SRT, I will leave it to the NA guys to give you the best advice, but hopefully this will get you going in the right direction.