HID was the best thing other then the Honda widow visors I have put on the car.
I could not beleive that I drove around for 3.5 years with those crap ass stock headlights

Pick up a good hid kit thats plug and play and you'll never regret it.

as for power mods... I guess the oem jdm 4-1 (with heat sheild) smsp test pipe and bottle neck adapter was the most usable and noticable power mod yet. and the price was just around 500 maybe a bit more.

If I were you I'd save some money and get a used HID kit, and spend the rest on going to a HPDE. now thats were you will learn to make the car faster