The thing a lot of people are forgetting, is they want to do it with out turbos, superchargers, or nitrous. Sure an SRT4 can easily be made fast, but its turbocharged. Same thing for Evos, and STIs. They all have forced induction, thus making them easily tuned to big hp.

The best example of a normally aspirated 4 cylinder that makes good hp is the Honda S2000. Its a normally aspirated 2 liter that makes 240hp. From what I've heard that motor is almost maxed out as a N/A motor.

I'd also add that when it comes to N/A 4 cylinder motors a Honda will always be better than a mopar. All that being said, I'm sure it could be done, but it would be retarded expensive. And it probably would not be even close to being a sleeper.