Is your engine friendly? Is it bubbly and out going? Or is it reserved and shy? Just exactly how would you describe your engine's personality? When I ask about your engine's personality, I was not actually asking about its social skills but rather how it behaves under the hood of your car. Does your engine make lots of low-end torque but run out of poop in the higher rpms? Or does it not make any decent power until the engine is spinning nearly at its redline? The manner in which your engine behaves is mostly dependant on the cam and changing cams can change your engine's personality.
A quick review, the cam (or cams in a multiple cam engine) are the lumpy looking sticks that open and close the valves that allow air and fuel into the engine and the exhaust gasses out. By changing the cam you can change the timing and the amount of the opening and closing of the valves. In turn, this changes the engine's personality.
To give you an idea of the range of personalities that an engine can have, think about a truck or heavy vehicle that needs a lot of "grunt" at low speeds to get rolling from a stop. They would have a cam that allows an engine to build torque quickly at low rpms. While a racecar is concerned with making peak power at high rpms and never dips down into low engine speeds. A street car's engine ideally has low end torque for stop and go driving with power for highway speeds so the manufacturers compromise on the cam design to give a little of both to a street car's engine.
Until about 20 years ago, an engine had a cam and that gave the engine a single personality. But the car manufacturers have come up with a variety of methods to change the cam's timing (called variable cam timing or variable valve timing) while the engine is running and in turn this allowed the engine to have a broader range of personalities. Today it is common for a newly purchased street car to be able to deliver low-end grunt and high rpm power with a cam that changes its relationship to the engine via variable cam or valve timing.
On some engines you can change the way the stock cam relates to the rest of the engine by changing the cam's timing. By using an add-on adjuster, it is possible to advance or retard a cam's timing. This will move a cam's peak power point either higher or lower in the rpm band. But this is a minor adjustment and does not give the same results of changing the cam to an entirely new profile.
On my 1987 CRX Si, the stock cam was a compromise of OK low-end torque, better high-end power and reasonable gas mileage. I swapped in a www.webcamshafts.com cam of a slightly more aggressive nature and it turned a pretty good performing engine into a real tiger.
So change your cam and change your engine's personality.