ok, so lets say you get a decent header and larger exhaust pipes, high flow cat, and nice muffler. you also get a cold/warm air induction kit for it as well. how much horsepower can you expect to gain? i read anywhere from 10-25, but i want someone's actual experience with it. i have a 2005 cavalier 2.2L ecotec. any information regarding simple bolt ons for this car would also be helpful.