You need a CAI to open up the airflow. The stock intake has crimps back towards the throttle body, it simply cannot allow enough air through.

Then you need a pulley mod of some kind that will spin the supercharger faster and create more boost.

After that you can be more creative... A computer tune, maybe exhaust work, maybe modify the cooling system, theres plenty of ideas.

But hey, just a word of advice. I completely regretted modifying my srt-6. It became expensive and time-consuming. I know people will disagree but its my own personal experience. So make sure you're truly bored with your car before you start modding because if you're just bored with life in general then put your money into some other hobby instead of the srt-6. Its just my personal opinion though... I regret modding my srt6 which is now gone, and regret modifying my '05 mustang gt which is long gone. Lesson learned for me.

EDIT: Oh yeah, I used a 100mm idler to tighten up my belt after installing the code3, so if you have belt slippage then thats an option. I don't believe I had any slippage in the first place though.