what sorta gains should i get from...

cai, headers, catback, under drive pulleys, lightned flywheel + fpr?
plus is there anything else i can do with out messin round with the internals?
im thinking bout 25-30hp increase with all that? waht do you guys think?
plus how hard is it to install camgears? and how much does it cost to have em installed? ive heard the aem ones arent good, is this true? id like to get camgears cuz i hear they make a decent hp increase
thanks