Join Date: Dec 2010
Location: The Great Big Box
Not a whole lot can be done, but what can be done has to be done altogether to increase power output. Not one single component or upgrade will yield a lot of power. The simplest way to get 5-10hp (or rather gain it back) is to go with an electric fan rather than use the factory steel fan. That's the biggest HP gain, unfortunately. The most I've seen someone get out of their 2.5L is about 40hp, but that was with close to a thousand dollars in components. For about $1500 you could swap in an entirely new driveline and be done with the 2.5L.
Or you can get used to driving a 4 cylinder powered brick. It has enough guts to mosey along at 65mph, even on stock gears with slightly bigger tires. Too big a tire will eat up your engines power really quick.
All about that unibody life.