I've got a 2011 300c that I absolutely love but, I want more power. I'm not sure about an exact power figure but in her current form (93 octane diablosport tune) she's fun but isn't quite to the "scary" level that I was hoping for when buying my first v8 car. I was wondering what steps should I take next to get to the "scary" level when I nail it.
Cam and headers will wake up a 5.7 considerably, not sure if it would be considered scary, but it will pull a lot stronger.
How many miles on the engine? Have you checked compression? That could give you an idea if boost is an option or what would be needed to get it ready.
Since 2011 is already VVT, a 392 could go in without too much hassle, Do you live in a highly regulated state, or a place where you are free to mod your car?
As Snobrdrdan mentioned, be prepared to drop some money if you start modding it. If you get to "scary" power levels, you will need a differential, driveshaft, possibly brake conversion, etc. I am in the process of putting way more money into my car than its worth, but that's because I need a wagon.