remove EGR (~9whp so i've heard), port and polish the head and match port the intake manifold, advance timing, remove secondary intake butterflies.
total so far= $0 & a few hours of time
or you could do cheap intake off ebay, LED washer nozzles, and a huge aluminum/faux carbon fiber 11" spoiler.
total cost= $200 & a loss of self respect.

But on the real...Mods cost money, this question has been asked countless times, when i was a newbie, i probably even asked it (can't remember due to my drinking habbits). the first thing i like to do to an engine is let it breath better; i.e. intake, exhaust, header. then i like to lessen the power used to turn the engine; i.e. Lightweight pulleys, flywheel, lose the clutch fan-get 2 electrics. Then i build the more serious internals up.
So??? What's your decided plan of action?