performance for a 2.4

I have a 2004 stratus with a 2.4. I was wondering if anyone out there new of any performance parts for this engine. Also i read somewhere that the horsepower was suppose to be 150 \, but i can not get anywhere near that mark..This is even after i changed the air intake to k&N. I did have to make it my self. It helped a lot but not nearly enough
Thanks

change your exhaust if you havent already. doesnt matter what you do to the engine wont make it to much faster when you have the stosk exhauston. it is a really big restrictor. thats the first thing you should of done.