Looking for input

I have a 99gc 4.0 Recently i've been hunting for budget horsepower here and there and think have been doing well so far. Right now the most expensive was the k&N fipk 250. and since then i've added 62mm throttle body 80 1in spacer 35 and just a holley afterburner muffler 35 i'm wondering if adding some longer rocker arms would be another nice inexpensive boost or if i shouldn't waste my time and do a cam. the only thing is i don't want to drain the ac system. either way i'd like to know what you guys think or let me know what you've done to your mills
Thanks